Miranda, L.S., A.G. Collins, Y.M. Hirano, C.E. Mills, and A.C. Marques. 2016. Comparative internal anatomy of Staurozoa (Cnidaria) with functional and evolutionary inferences. PeerJ 4:e2594; DOi 10.7717/peerj.2594.

Comparative efforts to understand the body plan evolution of stalked jellyfishes are scarce. Most characters, and particularly internal anatomy, have neither been explored for the class Staurozoa, nor broadly applied in its taxonomy and classification. Recently, a molecular phylogenetic hypothesis was derived for Staurozoa, allowing for the first broad histological comparative study of staurozoan taxa. This study uses comparative histology to describe the body plans of nine staurozoan species, inferring functional and evolutionary aspects of internal morphology based on the current phylogeny of Staurozoa. We document rarely- studied structures, such as ostia between radial pockets, intertentacular lobules, gametoducts, pad-like adhesive structures, and white spots of nematocysts (the last four newly proposed putative synapomorphies for Staurozoa). Two different regions of nematogenesis are documented. This work falsifies the view that the peduncle region of stauromedusae only retains polypoid characters; metamorphosis from stauropolyp to stauromedusa occurs both at the apical region (calyx) and basal region (peduncle). Intertentacular lobules, observed previously in only a small number of species, are shown to be widespread. Similarly, gametoducts were documented in all analyzed genera, both in males and females, thereby elucidating gamete release. Finally, ostia connecting adjacent gastric radial pockets appear to be universal for Staurozoa. Detailed histological studies of medusozoan polyps and medusae are necessary to further understand the relationships between staurozoan features and those of other medusozoan cnidarians.


Miranda, L.S., Y.M. Hirano, C.E. Mills, A. Falconer, D. Fenwick, A.C. Marques, and A.G. Collins. 2016. Systematics of stalked jellyfishes (Cnidaria: Staurozoa). PeerJ, DOi 10.7717/peerj.1951.

Staurozoan classification is highly subjective, based on phylogeny-free inferences, and suborders, families, and genera are commonly defined by homoplasies. Additionally, many characters used in the taxonomy of the group have ontogenetic and intraspecific variation, and demand new and consistent assessments to establish their correct homologies. Consequently, Staurozoa is in need of a thorough systematic revision. The aim of this study is to propose a comprehensive phylogenetic hypothesis for Staurozoa, providing the first phylogenetic classification for the group. According to our working hypothesis based on a combined set of molecular data (mitochondrial markers COI and 16S, and nuclear markers ITS, 18S, and 28S), the traditional suborders Cleistocarpida (animals with claustrum) and Eleutherocarpida (animals without claustrum) are not monophyletic. Instead, our results show that staurozoans are divided into two groups, herein named Amyostaurida and Myostaurida, which can be distinguished by the absence/presence of interradial longitudinal muscles in the peduncle, respectively. We propose a taxonomic revision at the family and genus levels that preserves the monophyly of taxa. We provide a key for staurozoan genera and discuss the evolution of the main characters used in staurozoan taxonomy.


Moroz, L.L., K.M. Kocot, M.R. Citarella, S. Dosung, T.P. Norekian, I.S. Povolotskaya, A.P. Grigorenko, C. Dailey, E. Berezikov, K. M. Buckley, A. Ptitsyn, D. Reshetov, K. Mukherjee, T.P. Moroz, Y. Bobkova, F. Yu, V.V. Kapitonov, J. Jurka, Y.V. Bobkov, J.J. Swore, D.O. Girardo, A. Fodor, F. Gusev, R. Sanford, R. Bruders, E. Kittler, C.E. Mills, J.P. Rast, R. Derelle, V.V. Solovyev, F.A. Kondrashov, B.J. Swalla, J.V. Sweedler, E.I. Rogaev, K.M. Halanych, and A.B. Kohn, 2014. The ctenophore genome and the evolutionary origins of neural systems. Nature (June 5, 2014): 109-114. Published online May 21, 2014; corrected online June 4, 2014.

The origins of neural systems remain unresolved. In contrast to other basal metazoans, ctenophores (comb jellies) have both complex nervous and mesoderm-derived muscular systems. These holoplanktonic predators also have sophisticated ciliated locomotion, behaviour and distinct development. Here we present the draft genome of Pleurobrachia bachei, Pacific sea gooseberry, together with ten other ctenophore transcriptomes, and show that they are remarkably distinct from other animal genomes in their content of neurogenic, immune and developmental genes. Our integrative analyses place Ctenophora as the earliest lineage within Metazoa. This hypothesis is supported by comparative analysis of multiple gene families, including the apparent absence of HOX genes, canonical microRNA machinery, and reduced immune com- plement in ctenophores. Although two distinct nervous systems are well recognized in ctenophores, many bilaterian neuron-specific genes and genes of ‘classical’ neurotransmitter pathways either are absent or, if present, are not expressed in neurons. Our metabolomic and physiological data are consistent with the hypothesis that ctenophore neural systems, and possibly muscle specification, evolved independently from those in other animals.


Purushothaman, J., L. Al Kharusi, C.E. Mills, H. Ghielani, and M. Al Marzouki, 2013. Timoides agassizii Bigelow, 1904, little-known hydromedusa (Cnidaria), appears briefly in large numbers off Oman, March 2011, with additional notes about species of the genus Timoides. Zootaxa, 3746 (2): 372-382.

A bloom of the hydromedusan jellyfish, Timoides agassizii, occurred in February 2011 off the coast of Sohar, Al Batinah, Sultanate of Oman, in the Gulf of Oman. This species was first observed in 1902 in great numbers off Haddummati Atoll in the Maldive Islands in the Indian Ocean and has rarely been seen since. The species appeared briefly in large numbers off Oman in 2011 and subsequent observation of our 2009 samples of zooplankton from Sohar revealed that it was also present in low numbers (two collected) in one sample in 2009; these are the first records in the Indian Ocean north of the Maldives. Medusae collected off Oman were almost identical to those recorded previously from the Maldive Islands, Pap- ua New Guinea, the Marshall Islands, Guam, the South China Sea, and Okinawa. T. agassizii is a species that likely lives for several months. It was present in our plankton samples together with large numbers of the oceanic siphonophore Physalia physalis only during a single month’s samples, suggesting that the temporary bloom off Oman was likely due to the arrival of mature, open ocean medusae into nearshore waters. We see no evidence that T. agassizii has established a new population along Oman, since if so, it would likely have been present in more than one sample period. We are unable to deduce further details of the life cycle of this species from blooms of many mature individuals nearshore, about a century apart. Examination of a single damaged T. agassizii medusa from Guam, calls into question the existence of its congener, T. latistyla, known only from a single specimen. **ask for a copy**


Appeltans, W., S.T. Ahyong, G. Anderson, M.V. Angel, T. Artois, N. Bailly, R. Bamber, A. Barber, I. Bartsch, A. Berta, M. Blazewicz-Paszkowycz, P. Bock, G. Boxshall, C.B. Boyko, S. Nunes Brandão, R.A. Bray, N.L. Bruce, S.D. Cairns, T-Y. Chan, L. Cheng, A.G. Collins, T. Cribb, M. Curini-Galletti, F. Dahdouh-Guebas, P.J.F. Davie, M.N. Dawson, O. De Clerck, W. Decock, S. De Grave, N.J. de Voogd, D.P. Domning, C.C. Emig, C. Erséus, W. Eschmeyer, K. Fauchald, D.G. Fautin, S.W. Feist, C.H.J.M. Fransen, H. Furuya, O. Garcia-Alvarez, S. Gerken, D. Gibson, A. Gittenberger, S. Gofas, L. Gómez-Daglio, D.P. Gordon, M.D. Guiry, F. Hernandez, B.W. Hoeksema, R.R. Hopcroft, D. Jaume, P. Kirk, N. Koedam, S. Koenemann, J.B. Kolb, R.M. Kristensen, A. Kroh, G. Lambert, D.B. Lazarus, R. Lemaitre, M. Longshaw, J. Lowry, E. Macpherson, L.P. Madin, C. Mah, G. Mapstone, P.A. McLaughlin, J. Mees, K. Meland, C.G. Messing, C.E. Mills, T.N. Molodtsova, R. Mooi, B. Neuhaus, P.K.L. Ng, C. Nielsen, J. Norenburg, D.M. Opresko, M. Osawa, G. Paulay, W. Perrin, J.F. Pilger, G.C.B. Poore, P. Pugh, G.B. Read, J.D. Reimer, M. Rius, R.M. Rocha, J.I. Saiz-Salinas, V. Scarabino, B. Schierwater, A. Schmidt-Rhaesa, K.E. Schnabel, M. Schotte, P. Schuchert, E. Schwabe, H. Segers, C. Self-Sullivan, N. Shenkar, V. Siegel, W. Sterrer, S. Stöhr, B. Swalla M.L. Tasker, E.V. Thuesen, T. Timm, M.A. Todaro, X. Turon, S. Tyler, P. Uetz, J. van der Land, B. Vanhoorne, L.P. van Ofwegen, R.W.M. van Soest, J. Vanaverbeke, G. Walker-Smith, T.C. Walter, A. Warren, G.C. Williams, S.P. Wilson, and M.J. Costello, 2012. The magnitude of global marine species diversity. Current Biology, 22: 1-14.

The question of how many marine species exist is important because it provides a metric for how much we do and do not know about life in the oceans. We have compiled the first register of the marine species of the world and used this baseline to estimate how many more species, partitioned among all major eukaryotic groups, may be discovered. There are ~226,000 eukaryotic marine species described. More species were described in the past decade (~20,000) than in any previous one. The number of authors describing new species has been increasing at a faster rate than the number of new species described in the past six decades. We report that there are ~170,000 synonyms, that 58,000–72,000 species are collected but not yet described, and that 482,000–741,000 more species have yet to be sampled. Molecular methods may add tens of thousands of cryptic species. Thus, there may be 0.7–1.0 million marine species. Past rates of description of new species indicate there may be 0.5 +/- 0.2 million marine species. On average 37% (median 31%) of species in over 100 recent field studies around the world might be new to science. We conclude that currently, between one-third and two-thirds of marine species may be undescribed, and previous estimates of there being well over one million marine species appear highly unlikely. More species than ever before are being described annually by an increasing number of authors. If the current trend continues, most species will be discovered this century.


Condon, R.H., W.M. Graham, C.M. Duarte, K.A. Pitt, C.H. Lucas, S.H.D. Haddock, K.R. Sutherland, K.L. Robinson, M. N. Dawson, M.B. Decker, C.E. Mills, J.E. Purcell, A. Malej, H. Mianzan, S. Uye, S. Gelcich, L.P. Madin. 2012. Questioning the rise of gelatinous zooplankton in the world’s oceans. BioScience 62: 161-169.

During the past several decades, high numbers of gelatinous zooplankton species have been reported in many estuarine and coastal ecosystems. Coupled with media-driven public perception, a paradigm has evolved in which the global ocean ecosystems are thought to be heading toward being dominated by "nuisance" jellyfish. We question this current paradigm by presenting a broad overview of gelatinous zooplankton in a historical context to develop the hypothesis that population changes reflect human-mediated alteration of global ocean ecosystems. To this end, we synthesize information related to the evolutionary context of contemporary gelatinous zooplankton blooms, the human frame of reference for changes in gelatinous zooplankton populations, and whether sufficient data are available to have established the paradigm. We conclude that the current paradigm in which it is believed that there has been a global increase in gelatinous zooplankton is unsubstantiated, and we develop a strategy for addressing the critical questions about long-term, human-related changes in the sea as they relate to gelatinous zooplankton blooms.**PDF file**


Miranda, L.S., M.A. Haddad, C.E. Mills and A.C. Marques. 2012. Lucernariopsis capensis Carlgren, 1938 (Cnidaria, Staurozoa) in Brazil: first record outside its type locality in South Africa.  Zootaxa 3158: 60-64.

Staurozoa is a class of Cnidaria comprising stalked, benthic jellyfishes that encompasses about 51 species. Stauromedusae are distributed worldwide, but are more common in temperate and polar waters. Taxonomic knowledge of these cnidarians is inadequate, as is information on their biology and ecology, probably because of their cryptic habit and general inconspicuousness. Consequently, scarcity of material renders their taxonomy even more difficult, demanding basic knowledge of their life cycle and intraspecific morphological variation. Revisions of unique records of unidentified species and more complete studies of species known only from original descriptions, sometimes based on few individuals, are necessary and can produce interesting information. Among such poorly known species is Lucernariopsis capensis Carlgren 1938, known only from its original description based on a single specimen from South Africa. A second individual of this staurozoan, collected in Brazil during 1985, has only recently been identified. The goal of this study is to describe the specimen, thereby advancing intraspecific knowledge of this lineage. **ask for a copy**


Zagal, C.J., Y.M Hirano, C.E. Mills, G.J. Edgar and N.S. Barrett, 2011. New Records of Staurozoa from Australian coastal waters, with a description of a new species of Lucernariopsis Uchida, 1929 (Cnidaria, Staurozoa, Stauromedusae) and a key to Australian Stauromedusae. Marine Biology Research 7: 651-666.

Four live species of Stauromedusae, including a new species (Depastromorpha africana, Lucernariopsis tasmaniensis sp. nov., Stenoscyphus inabai and Lipkea sp.) are described from the East coast of Tasmania and New South Wales, Australia. These medusae are the first staurozoan records for Tasmania and include three new records for Australia. Stauromedusae were found on the algae Caulerpa spp., Macrocystis pyrifera and rocky reef substratum covered by epibiota. Depastromorpha africana and L. tasmaniensis sp. nov. were abundant at few study sites and were categorized as spatially rare at the local scale of this study. Stenoscyphus inabai and Lipkea sp. were not encountered at the study sites so their exact range distribution could not be established. Their morphologies are compared in a key to Australian Stauromedusae including photographic evidence. Previously unpublished museum records and personal observations are also included, increasing the distribution of D. africana to New Zealand, South Australia and Tasmania and the genera Lucernariopsis and Lipkea to Australia. Morphological differences in the number and distribution of tentacle-like structures along the margin of the arms of Lipkea sp. and their congeners elsewhere suggest that they are new species of Stauromedusae, but collection and detailed examination is necessary to determine their identity. These results support increasing evidence that the distribution and diversity of Staurozoa are much greater than that currently recorded in the literature, especially in the Southern Hemisphere. **PDF file**


Byern, J. von, C.E. Mills and P. Flammang, 2010. Bonding tactics in ctenophores ­­ morphology and function of the colloblast system. pp. 29-40. In Biological Adhesive Systems: From Nature to Technical and Medical Application (J. von Byern and I. Grünwald, editors). Springer Publishing Company, New York, 305 pp.

This book chapter reviews the state of knowledge on colloblasts, the sticky microscopic adhesive cells on the tentacles of ctenophores, or comb jellies, which are used for prey capture. Most species of ctenophores have a pair of tentacles, usually with many sidebranches. These tentacles, with a couple of exceptions, are covered with many thousands of colloblasts. The colloblasts have a rounded head covered with adhesive granules and a conical stalk with helical thread that roots the entire structure in the tentacle epithelium. Tentacle morphology, the associated sensory system, and colloblast ultrastructure, development, polymorphism, and capture behavior are discussed. Some new images of this little-studied, but highly complex, colloblast system are included.


Mianzan, H., E.W. Dawson and C.E. Mills, 2009. Phylum Ctenophora: Comb Jellies. pp. 49-58. In New Zealand Inventory of Biodiversity. Volume One. Kingdom Animalia: Radiata, Lophotrochozoa, and Deuterostomia (D.P. Gordon, editor). Canterbury University Press, Christchurch.

Part of a millenium inventory of all living species in New Zealand, this chapter contains a review of the biology of ctenophores and a checklist of the 19 species that so far have been collected in New Zealand (marine) waters. The chapter includes a history of studies on New Zealand Ctenophora, and the present status of knowledge with suggestions for future studies. The ctenophore fauna of New Zealand has received relatively little attention and would undoubtedly prove an interesting and rewarding project for further research. **PDF file**


Mills, C.E., 2008.  Ctenophora. pp. 102-104. In Checklist delle specie della fauna italiana, second edition. (G. Relini, editor). Biol. Mar. Mediterr., 15 (suppl.): 104-106.

This chapter represents a minor update of Mills, C.E., 1995, Ctenophora, In Checklist delle specie della fauna italiana. The only change is the new presence of the American ctenophore Mnemiopsis leidyi in Italian waters, following its introduction into the Black Sea in the early 1980s. This species was reported in the northern Adriatic Sea in 2009 and is suspected to be present elsewhere in Italian waters, as it moves through the western Mediterranean.


Mills, C.E. 2008. Management plan for the University of Washington's Cedar Rock Preserve on Shaw Island, San Juan County, Washington. Online publication, 82 pp. **PDF file**

Cedar Rock Preserve is a 370 acre property composed of 10 contiguous parcels on the south side of Shaw Island, Washington. It is part forest, part open fields, and edged along approximately two-thirds of its boundary by shoreline of gravel beaches alternating with long stretches of low-to-medium bank bedrock. This property was farmed until the mid-1970s, when it was given by Robert Ellis to the University of Washington to "be held, used and maintained as a nature preserve for scientific, educational, research and aesthetic purposes, and ... kept in the natural state without disturbance of the native plant, bird and animal populations and habitat." In addition to the Cedar Rock Preserve, the University of Washington holds another 500 acre preserve on Shaw Island and another 500 acres of uplands biological preserve on San Juan Island. The overarching goals for all of these properties are to maintain and restore native biodiversity and ecosystem function and to facilitate education and research that is consistent with these goals; a secondary goal is to maintain important parts of the cultural landscape.
This management plan inventories the parcels and ammenities at Cedar Rock, discusses relevant San Juan County regulations and long range planning issues relevant to its future, visitor policies, environmental and cultural history, aquifers and soils, forests and other distinct vegetation stands, and view corridors. It lists some agents of change that will influence the future of the Preserve, and then gives some specific goals and management prescriptions relevant to the state of the Preserve in 2008, as well as listing the management target activities for years 2004-2009 as the management plan was being developed. The document concludes with 5-year, 10-year and 100-year visions for the Cedar Rock Preserve. Appendices include lists of animals and plants found on the Cedar Rock Preserve.


Mills, C.E. and Y.M. Hirano, 2007. Hydromedusae. pp. 286-288. In Encyclopedia of Tidepools and Rocky Shores (M.W. Denny and S.D. Gaines, editors). University of California Press, Berkeley.

This is a chapter in an encyclopedia which attempts global coverage of organisms and processes associated with tidepools and intertidal rocky shores along the world's coastlines. The only hydrozoan jellyfishes likely to be living along rocky shores are a group of tiny medusae sometimes known as the crawling or creeping hydromedusae, which belong to the genera Staurocladia and Eleutheria. These hydromedusae, after being released from their hydroids, are adapted to remain attached to the bottom by their tentacles, which they use to crawl slowly around on seaweeds or other substrates. These are very tiny species, the largest of which is no more than a few millimeters across the flattened central disk. In the rocky intertidal, crawling hydromedusae are perhaps most often encountered in tidepools, but some may also be found by the careful observer to be hanging on tightly to rock or seaweeds, even in places of moderate wave action. There are 17 species, known to occur in Japan, Hawaii, New Zealand, Australia, Papua New Guinea, the Seychelles, Kerguelen Island in the southern Indian Ocean, several locations in Antarctica, South Georgia, South Africa, Chile, Brazil, Falkland Islands, Bermuda, several locations in the European North Atlantic, the Mediterranean, Black Sea, and perhaps also a single sighting from the Caribbean. **PDF file**


Mills, C.E. and Y.M. Hirano, 2007. Stauromedusae. pp. 539-541. In Encyclopedia of Tidepools and Rocky Shores (M.W. Denny and S.D. Gaines, editors). University of California Press, Berkeley.

This is a chapter in an encyclopedia which attempts global coverage of organisms and processes associated with tidepools and intertidal rocky shores along the world's coastlines. It includes a short review of the biology, ecology, morphology and life history of a group of little-studied animals called stauromedusae. Stauromedusae are small jellyfishes that spend their entire life attached to a substrate (usually rock or seaweed) rather than swimming freely up into the water column like most other jellyfish. Although a few of the larger, often colorful, freeliving scyphomedusae could end up stranded in tidepools, most of the jellyfishes likely to be found permanently living along the rocky shore are the little attached jellyfishes known as Stauromedusae, or Staurozoa. (There are also some very tiny crawling jellyfishes found along some rocky shores, which are hydromedusae - see article above.) Most stauromedusae are found in the intertidal or shallow subtidal and are cryptically colored, so they may be difficult to see. Five species with different morphologies are illustrated. **PDF file**


Marques, A.C., A.E. Migotto, D.R. Calder and C.E. Mills, 2007. Key to the polypoid stages of Hydrozoa. pp. 118-137 and 151-168, with 11 plates. In Light and Smith's Manual: Intertidal Invertebrates of the Central California Coast. Fourth Edition (J.T. Carlton, editor). University of California Press, Berkeley.

This is a chapter in a book containing technical, dichotomous keys for the identification of marine intertidal invertebrates of the Pacific coast of the United States, from about Coos Bay, Oregon to Santa Barbara, California. The key to polypoid stages of Hydrozoa includes species known from the intertidal and very shallow subtidal, as well as a few species known only from laboratory culture whose depth range in the field is not known. Eighty-seven species of hydroids (some keyed out only to the genus level) can be identified using these keys. An extensive glossary and labelled diagrams are provided, as well as ten full-page plates of pen and ink illustrations of 94 hydroid species. The annotated species list, arranged by family, includes individual notes on the biogeography and biology of 154 species (or genera) of Hydrozoa (combining hydroids and hydromedusae into one list, along with 28 additional species or genera of siphonophores) including several species that are not in the key, but might be expected in nearby waters outside the range of this book. **PDF file (This is an electronic version of the entire Chapter 10, Cnidaria, published in Light and Smith's Manual: Intertidal Invertebrates of the Central California Coast. Fourth Edition (J.T. Carlton, editor), Berkeley: University of California Press, 2007. To purchase a copy of this book or for permission to reproduce or reprint this material, visit www.ucpress.edu.)**


Mills, C.E. and J.T. Rees, 2007. Hydromedusae. pp. 137-168, with 9 plates. In Light and Smith's Manual: Intertidal Invertebrates of the Central California Coast. Fourth Edition (J.T. Carlton, editor). University of California Press, Berkeley.

This is a chapter in a book containing technical, dichotomous keys for the identification of marine intertidal invertebrates of the Pacific coast of the United States, from about Coos Bay, Oregon to Santa Barbara, California. Hydromedusae are not likely to be found in the intertidal zone, unless stranded, so we included in the Hydromedusa key species that are most likely to be encountered around marinas, stranded on beaches, or found nearshore at the surface by divers and observers from boats. Eighty-nine species of hydromedusae (a few keyed out only to the genus level) can be identified using these keys. An extensive glossary and labelled diagrams are provided, as well as eight full-page plates of species illustration. Two of the plates are composites containing black and white photographs of 21 of the species; six more plates include pen and ink illustrations of 71 more species. The annotated species list, arranged by family, includes individual notes on the biogeography and biology of 154 species (or genera) of Hydrozoa (combining hydroids and hydromedusae into one list, along with 28 additional species or genera of siphonophores) including several species that are not in the key, but might be expected in nearby waters outside the range of this book. **PDF file (This is an electronic version of the entire Chapter 10, Cnidaria, published in Light and Smith's Manual: Intertidal Invertebrates of the Central California Coast. Fourth Edition (J.T. Carlton, editor), Berkeley: University of California Press, 2007. To purchase a copy of this book or for permission to reproduce or reprint this material, visit www.ucpress.edu.)**


Mills, C.E., S.H.D. Haddock, C.W. Dunn and P. R. Pugh, 2007. Siphonophores. pp. 150-154 and 164-166, with 3 plates. In Light and Smith's Manual: Intertidal Invertebrates of the Central California Coast. Fourth Edition (J.T. Carlton, editor). University of California Press, Berkeley.

This is a chapter in a book containing technical, dichotomous keys for the identification of marine intertidal invertebrates of the Pacific coast of the United States, from about Coos Bay, Oregon to Santa Barbara, California. Siphonophores are not likely to be found in the intertidal, unless stranded, so we included in the Siphonophora keys about twenty species (some keyed out only to the genus level) that are most likely to be encountered nearshore at the surface, by divers, observers from boats, and even the most common species that might be collected in nearshore deep trawls, or as beached fragments. An extensive glossary is provided, as well as pen and ink illustrations of 25 species; black and white photographs of seven of the species, live and intact, are shown in a single, composite full-page plate. An annotated species list at the end of the section on Hydrozoa integrates the Siphonophora with the rest of the Hydrozoa (hydroid polyps and hydromeduse) and includes notes on the biogeography and biology of 28 species or genera of west coast siphonophores, including a few which are likely to be found south of the range covered by this book and do not otherwise occur in the key. **PDF file (This is an electronic version of the entire Chapter 10, Cnidaria, published in Light and Smith's Manual: Intertidal Invertebrates of the Central California Coast. Fourth Edition (J.T. Carlton, editor), Berkeley: University of California Press, 2007. To purchase a copy of this book or for permission to reproduce or reprint this material, visit www.ucpress.edu.)**


Mills, C.E. and R.J. Larson, 2007. Scyphozoa: Scyphomedusae, Stauromedusae, and Cubomedusae. pp. 168-173, with 3 plates. In Light and Smith's Manual: Intertidal Invertebrates of the Central California Coast. Fourth Edition (J.T. Carlton, editor). University of California Press, Berkeley.

This is a chapter in a book containing technical, dichotomous keys for the identification of marine intertidal invertebrates of the Pacific coast of the United States, from about Coos Bay, Oregon to Santa Barbara, California. Keys are provided for the identification of seven species of large scyphomedusae (jellyfish) that may be found nearshore along much of the American Pacific coast, and also for seven species of attached stauromedusae that can be found in the intertidal or shallow subtidal between central Oregon and central California. An annotated species list includes notes on the biogeography and biology of 21 west coast Scyphomedusae, Stauromedusae, and (one) Cubomedusae including a few species that may be occasional visitors on the south end of the range of this book and that are not otherwise in the keys. This chapter includes a glossary, labelled diagram of a scyphomedusa, pen and ink illustrations of the two common species of Aurelia on the west coast, and black and white photographs of four species of stauromedusae. **PDF file (This is an electronic version of the entire Chapter 10, Cnidaria, published in Light and Smith's Manual: Intertidal Invertebrates of the Central California Coast. Fourth Edition (J.T. Carlton, editor), Berkeley: University of California Press, 2007. To purchase a copy of this book or for permission to reproduce or reprint this material, visit www.ucpress.edu.)**


Mills, C.E. and S.H.D. Haddock, 2007. Ctenophores. pp. 189-199, with 5 plates. In Light and Smith's Manual: Intertidal Invertebrates of the Central California Coast. Fourth Edition (J.T. Carlton, editor). University of California Press, Berkeley.

This is a chapter in a book containing technical, dichotomous keys for the identification of marine intertidal invertebrates of the Pacific coast of the United States, from about Coos Bay, Oregon to Santa Barbara, California. Ctenophores are not likely to be found in the intertidal, unless stranded, so we included in the Ctenophora key species that are most likely to be encountered nearshore at the surface, by divers, observers from boats, and even the most common species that might be collected in nearshore deep trawls. Twenty-six species of ctenophores can be identified using these keys, and the annotated species list includes notes on the biogeography and biology of these west coast ctenophores including two more species that may be occasional visitors on the south end of the range. An extensive glossary and labelled diagram is provided, as well as black and white photographs of 25 of the species in four, composite full-page plates. **PDF file (This is an electronic version of Chapter 11, Ctenophora, published in Light and Smith's Manual: Intertidal Invertebrates of the Central California Coast. Fourth Edition (J.T. Carlton, editor), Berkeley: University of California Press, 2007. To purchase a copy of this book or for permission to reproduce or reprint this material, visit www.ucpress.edu.)**


Wyllie-Echeverria, V.R. and C.E. Mills. 2005. Centennial plant collection: revisiting 1904 herbarium specimens from the San Juan Islands in 2004. Proceedings of the 2005 Puget Sound Georgia Basin Research Conference. Seattle,Washington. Short paper published online (P1. Puget Sound Biota).

For the occasion of the 100th anniversary of the University of Washington Friday Harbor Laboratories, we revisited a collection of University of Washington Herbarium specimens from the first summer of classes in the San Juan Islands in 1904. These constitute the earliest plant specimens from the San Juans presently in the UW Herbarium. Less than half of this herbarium collection is digitized online, but having discovered this unique database, we decided to see how many of the species could still be located at or near where they were collected 100 years ago. Searching the specimen labels that are available online, we found 42 species collected in San Juan County June to August 1904. Additional un-digitized 1904 specimens probably exist in the UW Herbarium collection. As many of the original sites as possible were revisited one hundred years later. Specimens were originally collected on seven islands (San Juan, Orcas, Stuart, Blakely, Wasp, Flat Top and John’s). We recollected 13 of the 42 species, most of which were present very near where they had been found in 1904. Some of the missing species have long been extirpated from the San Juans; a few others were in locations not accessible to us. **PDF file**


Mills, C.E. and C.O. Hermans, et al. Internet 2004-present. Historical Centennial Timeline for the University of Washington's Friday Harbor Laboratories 1903-2004.
Electronic internet document, available at http://faculty.washington.edu/cemills/FHLTimeline.html.
Published by the authors, web page established Nov. 2004, see web page for most recent update.

This approximately 30-page single-spaced history of the Friday Harbor Laboratories was prepared in part to celebrate the 100th anniversary of this marine biology field station in the San Juan Archipelago in the NW corner of Washington State, USA. It was first presented as text in the May-October 2004 exhibit about the Friday Harbor Laboratories at the San Juan Island Historical Museum in Friday Harbor. We are grateful to the late Tony Surina, San Juan Island freelance historian, who generously and carefully read through about 40 years of early San Juan Island newspapers, combing for articles about the Friday Harbor Labs; his efforts have provided many of the early details reported here. This history is not complete, but is an ongoing project, and can be expected to change substantially over the coming years; photographs will eventually be added. A hard-copy, illustrated version may eventually be made available.


Mills, C.E. and K. Rawson, 2004. Outlook grim for North Pacific Rockfish: Rockfish Symposium, Friday Harbor Laboratories, University of Washington, USA, September 25-26, 2003. Fish and Fisheries, 5: 1-3.

A Rockfish Symposium was held in Washington State by the San Juan County citizens' Marine Resources Committee in order for fisheries managers from the Pacific coast of North America, from California to British Columbia, to discuss the beleaguered status of nearly all of the more than 50 species of rockfish (Sebastes) that are characteristic of the NE Pacific shelf. Overfishing has reduced the stocks of most of these species to be dominated by young, small fish, with low reproductive output and poor recruitment. The outlook for recovery without serious intervention measures is poor. Regulations to encourage rockfish recovery must be targeted at all stages of the life cycle, and must include measures to mitigate impacts from pollution and habitat degradation as well as fishing. State and federal governments and local Indian/First Nations tribes, who share fishing rights and responsibilities in much of the affected region in the US and Canada will have to work together effectively to achieve these results. **PDF file (This is an electronic version of an article published in Fish and Fisheries: complete citation information for the final version of the paper, as published in the print edition of Fish and Fisheries, is available on the Blackwell Synergy online delivery service, accessible via the journal's website at http://www.blackwellpublishing.com/FAF or http://www.blackwell-synergy.com.)**


Mills, C.E., C.G. Mittermeier and S.A. Earle, 2003. Jellyfish and Ctenophore Blooms. pp. 274-279 In Wildlife Spectacles (Patricio Robles Gil, producer). CEMEX (Monterrey), Conservation International (Washington, D.C.), and Agrupación Sierra Madre (Mexico City).

Written for a conservation book celebrating the amazing phenomena of the various spectacular animal aggregations that occur worldwide, this short article is a primer about jellyfish and ctenophores and the kinds of aggregations that they form, usually in coastal waters. It summarizes for a general audience some of the natural and non-indigenous jellyfish blooms and cycles in the oceans that are detailed in the 2001 Mills "Jellyfish blooms" article abstracted below. The conservation status of jellyfish and ctenophores, some of the economic problems brought about by these blooms, and links to changing global fisheries are discussed. This article is accompanied by spectacular photographs of jellyfish blooms from different locations.


Cairns, S.D., D.R. Calder, A. Brinckmann-Voss, C.B. Castro, D.G. Fautin, P.R. Pugh, C.E. Mills, W.C. Jaap, M.N. Arai, S.H.D. Haddock and D.M. Opresko, 2002. Common and Scientific Names of Aquatic Invertebrates from the United States and Canada: Cnidaria and Ctenophora ­ Second Edition. American Fisheries Society, Special Publication #28, Bethesda, Maryland, 115 pp.

This is the second edition of a publication whose purpose is to standardize use of scientific and common names of American aquatic animals. The series began as a list of common names of fishes corresponding to their accepted scientific names. This book is a compilation of checklists of Cnidaria and Ctenophora, generated by experts in the field, for species found in North American waters - defined as: north of Mexico, to 320 km off the coast, and shallower than 200 m. Species included are those whose occurrence in this region has been authenticated in published accounts or verified by a specialist, based on specimens in an established research collection. The checklists provide a general guide to distribution, specifying for each of 1369 species: Atlantic Ocean (including the Gulf of Mexico), Pacific Ocean, Arctic Ocean, fresh water, estuarine, and introduced (nonindigenous) species. The checklists are followed by 24 pages of changes and annotations to the 1991 Edition, a brief section on endangered and threatened cnidarians of North America, several pages of references, an all-important index, and several pages of selected color photographs.


Cohen A.N., H.D. Berry, C.E. Mills, D. Milne, K. Britton-Simmons, M. J. Wonham, D. L. Secord, J. A. Barkas, B. Bingham, B. E. Bookheim, J. E. Byers, J. W. Chapman, J. R. Cordell, B. Dumbauld, A. Fukuyama, L. H. Harris, A. J. Kohn, K. Li, T. F. Mumford Jr., V. Radashevsky, A. T. Sewell, and K. Welch, 2001. Report of the Washington State Exotics Expedition 2000: A Rapid Assessment Survey of Exotic Species in the Shallow Waters of Elliott Bay, Totten and Eld Inlets, and Willapa Bay. Nearshore Habitat Program, Washington State Department of Natural Resources, Olympia, Washington, 46 pp.

We report here on a second survey of exotic organisms in Washington State waters, conducted May 17-23, 2000. The 2000 Expedition was the sixth in a series of Rapid Assessment surveys for exotic marine organisms in California and Washington. Three regions in Washington State were sampled to capture a range of oceanographic conditions and patterns of human use: Elliott Bay and the Duwamish River estuary are located in the Central Basin of Puget Sound, near the City of Seattle; Totten and Eld Inlets are relatively protected bays in the Southern Basin of Puget Sound, with predominant aquaculture and residential land uses; Willapa Bay is Washington's largest outer coast estuary and is the state's largest aquaculture center. As in past surveys, our primary objective was to assess the status of exotic invasions within defined regions and habitat types through nonquantitative census methods. Secondary objectives were to obtain data for comparisons between habitats and regions, and for comparisons with past surveys; to obtain baseline data for future assessments of changes in invasion status and the effectiveness of prevention or control efforts; to detect new invasions and document significant range extensions; and to identify new species. As of October 2001, 40 exotic species have been identified from the 2000 Expedition. Among the three regions, 15 exotic species were collected in each of the Elliott Bay and Totten/Eld Inlet regions, and 34 exotic species were collected in Willapa Bay. The apparent ecological dominance by exotics was slightly greater in Totten/Eld Inlets than in Elliott Bay, and much greater in Willapa Bay; thus the greatest number and extent of invasions was found in the least physically-altered system. The shipment and planting of oysters for commercial aquaculture is considered to be a possible mechanism responsible for introducing onto the Pacific Coast 35 of the 40 exotic species collected by the Expedition. In contrast, ballast water is considered a possible transport mechanism for 13 of the species, and all ship-associated mechanisms together (ship-fouling, solid ballast and ballast water) for 28 of the species. All of these mechanisms would also be effective at moving organisms between bays on the Pacific Coast. **PDF file**


Mills, C.E. 2001. Jellyfish blooms: are populations increasing globally in response to changing ocean conditions? Hydrobiologia, 451: 55-68.

By the pulsed nature of their life cycles, gelatinous zooplankton come and go seasonally, giving rise in even the most undisturbed circumstances to summer blooms. Even holoplanktonic species like ctenophores increase in number in the spring or summer when planktonic food is available in greater abundance. Beyond that basic life cycle-driven seasonal change in numbers, several other kinds of events appear now to be increasing the numbers of jellies present in some ecosystems. Over recent decades, man's expanding influence on the oceans has begun to cause real change and there is reason to think that in some regions, new blooms of jellyfish are occurring in response to some of the cumulative effects of these impacts. The issue is not simple and in most cases there are few data to support our perceptions. Examples of unpredicted increases in native jellyfish populations include Chrysaora melanaster in the Bering Sea, Chrysaora hysoscella in the Benguela Current, pelagic hydroid fragments in the Gulf of Maine, some scyphomedusae in the northern Gulf of Mexico, and a possible, but poorly documented, increase in pelagic Cnidaria and Ctenophora in the Southern Ocean. A different phenomenon is demonstrated by jellyfish whose populations regularly fluctuate, apparently with climate, causing periodic blooms: Pelagia noctiluca, with about a 12-year cycle in the Mediterranean Sea, is the best documented case with data going back two centuries; Stomolophus nomurai blooms at very long intervals (20-40 years) in the Sea of Japan. Perhaps the most damaging type of jellyfish increase in recent decades has been caused by populations of new, nonindigenous species gradually building-up to 'bloom' levels in some regions: examples include Rhopilema nomadica in the eastern Mediterranean Sea, Mnemiopsis leidyi ctenophores in the Black Sea and most recently Phyllorhiza punctata in the Gulf of Mexico. Blooms of Aurelia aurita in many locations worldwide may also prove to fall into this category when a genetic analysis is completed (the tight-aggregating behavior shown by Aurelia medusae helps further confuse the question of what is a bloom). Lest one conclude that the next millennium will feature only increases in jellyfish numbers worldwide, there are also examples in which populations are decreasing in heavily impacted coastal areas. These include most hydromedusae in the northern Adriatic Sea (population level decline), two of the five species in the Polyorchidae in the North Pacific, and population declines of Aequorea victoria in Washington State. Some jellyfish will undoubtedly fall subject to ongoing species elimination processes that already portend a vast global loss of biodiversity. Knowledge about the ecology of both the medusa and the polyp phases of each life cycle are necessary if we are to understand the true causes of these increases and decreases, but in most cases where changes in medusa populations have been recognized, we know nothing about the field ecology of its polyp. **PDF file**


Mills, C.E., A.N. Cohen, H.K. Berry, M.J. Wonham, B. Bingham, B. Bookheim, J.T. Carlton, J.W. Chapman, J. Cordell, L.H. Harris, T. Klinger, A.J. Kohn, C. Lambert, G. Lambert, K. Li, D.L. Secord, and J. Toft. 2000. The 1998 Puget Sound Expedition: a shallow water rapid assessment survey for nonindigenous species, with comparisons to San Francisco Bay. pp 130-138 In Marine Bioinvasions: Proceedings of the First National Conference, January 24-27, 1999 (Judith Pederson, editor), MIT Sea Grant Program, Cambridge, Massachusetts.

A rapid assessment survey for nonindigenous species at 23 primary stations and 8 secondary stations was conducted September 8­16, 1998 in the inland marine waters of Washington State from Blaine, at the Canadian border, to Olympia, in south Puget Sound. The 1998 Expedition team was composed of scientists with both broad and specific taxonomic and regional expertise from universities and local and state agencies. It included core researchers from the four San Francisco Bay Expeditions of 1993­1997, where the survey techniques were developed. Using a variety of sampling methods on marina docks and adjacent shallow water benthic habitats, the 1998 team collected and identified more than 400 native species and 39 nonindigenous species (3 plants and 36 invertebrates) -- taxonomic work on the samples is still underway. The number of nonindigenous species collected per site showed no obvious correlation with salinity, temperature or region. We believe that Puget Sound presently hosts more than 50 nonindigenous marine species. This is substantially fewer than the approximately 160 nonindigenous species known to be in the marine and estuarine portions of San Francisco Bay, excluding its associated Delta region. The vast difference in invasion level is noteworthy considering the close shipping links between these two estuaries for the past 150 years, although it is also partly a sampling artifact reflecting the different state of knowledge of nonindigenous species in the two estuaries.


Mills, C.E. and J.T. Rees, 2000. New observations and corrections concerning the trio of invasive hydromedusae Maeotias marginata (=M. inexpectata), Blackfordia virginica, and Moerisia sp. in the San Francisco Estuary. Scientia Marina, 64 (Suppl. 1): 151-155.

New observations of Maeotias, Blackfordia, and Moerisia in low salinity waters of the San Francisco Bay estuary allow better understanding of the life cycles and natural history of these three genera of invading hydrozoans. Maeotias inexpectata Ostroumoff, 1896 is found to be a junior synonym of Maeotias marginata (Modeer, 1791). Moreover, M. inexspectata Ostroumoff, 1896b is an incorrect subsequent spelling of M. inexpectata Ostroumoff, 1896a. The clear presence of marginal statocysts in the medusa of this species places it back in the family Olindiidae of the Limnomedusae. Polyps previously attributed to Maeotias in San Francisco Bay are now known to belong to a Moerisia sp., whose medusa has also recently been found in the estuary system. Solitary Moerisia polyps have been found in the field amongst the general fouling fauna on floating docks in the Napa River. Small simple primary polyps of M. marginata were obtained in the laboratory. Polyps of Blackfordia virginica have been found in abundance in the field covering the valves of nonindigenous barnacles in the Napa River and laboratory-cultured colonies are pictured here along with their newly-released and juvenile medusae. **PDF file**


Mills, C.E. 2000. The life cycle of Halimedusa typus with discussion of other species closely related to the family Halimedusidae (Hydrozoa, Capitata, Anthomedusae). Scientia Marina, 64 (Suppl. 1): 97-106.

The little-known Anthomedusa, Halimedusa typus has been collected from several locations in California, Oregon, and British Columbia on the Pacific coast of the United States. The adult medusa is redescribed based on new observations of living material and is found to have capitate tentacles. Polyps of H. typus were raised several times after spawning field-collected medusae in the laboratory; the cultures on one occasion lived for more than a year. The capitate polyp is solitary and very tiny, emerging from a basal perisarc measuring 200­300 µm in diameter. One cultured polyp produced a medusa, which is described. The taxonomic positions of several other morphologically-similar Anthomedusae in the Capitata are compared and discussed here. Tiaricodon coeruleus and Urashimea globosa are moved from the Polyorchidae to the Halimedusidae, and the similarity of Boeromedusa auricogonia (Boeromedusidae) to all of these medusae and to the genera Polyorchis, Scrippsia and Spirocodon of the family Polyorchidae is considered. The group of species under consideration is basically restricted to the Pacific Ocean, except for T. coeruleus and U. globosa, which have also been collected in the south Atlantic and south Atlantic/Antarctic. It is noted that medusae of the Halimedusidae are typically found quiescent near the surface, whereas those of the Polyorchidae either rest on the bottom or must continue pulsating to stay up in the water column, indicating a basic underlying difference in buoyancy and resultant behavior between the medusae in these two families. **PDF file**
See Acta Errata.


Mills, C.E., F. Boero, A. Migotto and J.M. Gili, editors, 2000. Trends in Hydrozoan Biology, IV. Scientia Marina, 64 (Suppl. 1), 284 pages. (Proceedings of the Fourth Workshop of the Hydrozoan Society, Bodega Bay, California.)

This volume represents the fourth in a series published following workshops of the international Hydrozoan Society. Having previously met in Ischia, Italy (September 1985), Blanes, Spain (September 1991) and Roscoff, France (September 1994), this time the Society decided to venture into the New World, holding its Fourth Workshop at the Bodega Marine Laboratory in Bodega Bay, central California, from September 19 to October 3, 1998. Fifty participants, representing 16 countries and professional levels from advanced undergraduate students to professors emeritus, contributed to the two week workshop. The Hydrozoan Society workshops provide a unique opportunity for those of us who study hydroids and hydromedusae, usually in comparative isolation, to really get to know each other at a personal level and to share ideas and promote future collaborations between people of similar interests, even if we come from different disciplines. This volume consists of 30 papers written by scientists living all over the world in highly different circumstances. The papers are all about Hydrozoa, but beyond that they represent a wide range of topics, and provide the reader with an overview of our knowledge and interests at the turn of the century and millenium.


Mills, C. E. 2000. Planktonic Cnidaria, Ctenophora, and pelagic Mollusca. p. 9c2-15 In Biological Invasions of Cold-water Coastal Ecosystems: Ballast-mediated Introductions in Port Valdez / Prince William Sound, Alaska. Final Project Report, presented to the Regional Citizens' Advisory Council of Prince William Sound, Valdez, Alaska (A. H. Hines and G. M. Ruiz, editors).

No known nonindigenous species of planktonic Cnidaria or Ctenophora were collected in Prince William Sound or Cook Inlet, Alaska, by scientific teams of taxonomic specialists in either 1998 or 1999. In the 1999 expedition, 15 species of Hydrozoa were collected (including 3 hydroids [see Calder/Henry report (?) for more thorough hydroid work-up] and 14 species of hydromedusae), two scyphomedusae and unidentified scyphozoan polyps (scyphistomae), and two species of ctenophores. Two molluscan species were also taken in the water column.


Brodeur, R.D., C. E. Mills, J.E. Overland, G.E. Walters and J.D. Schumacher, 1999. Evidence for a substantial increase in gelatinous zooplankton in the Bering Sea, with possible links to climate change. Fisheries Oceanography, 8: 296-306.

We examined quantitative catches of large medusae from summer bottom trawl surveys that sampled virtually the same grid station on the eastern Bering Sea shelf using the same methodology every year from 1979 to 1997. This series shows a gradual increase in biomass of medusae from 1979 to 1989, followed by a dramatic increase in the 1990s. The median biomass increased tenfold between the 1982-1989 and the 1990-1997 periods. Most of this biomass was found within the Middle Shelf Domain (50 < z < 100 m). The greatest rate of increase occurred in the north-west portion of this domain. Whether this dramatic increase in biomass of gelatinous zooplankton has resulted from some anthropogenic perturbation of the Bering Sea environment or is a manifestation of natural ecosystem variability is unclear. However, several large-scale winter/spring atmospheric and oceanographic variables in the Bering Sea exhibited concomitant changes beginning around 1990, indicating that a possible regime change occurred at this time. **PDF file**


Mills, C.E. Internet 1999-present. Stauromedusae: list of all valid species names.
Electronic internet document, available at http://faculty.washington.edu/cemills/Staurolist.html.
Published by the author, web page established Oct. 1999, see web page for most recent update.

This electronic document consists of a list of all stauromedusae (about 50 species) and their authors and dates that I have found in a rather extensive search of the literature, with consultation from Yayoi Hirano of Japan, who I believe to be the world expert on this group. Links are included to stauromedusa images (by species) located elsewhere on the web. This list is still an ongoing work and is subject to modification at any time; I welcome any additions or corrections that anyone may wish to submit. In many cases, I have listed older synonyms to good species names in parentheses on the line following. In order to be true to its in-progress nature, I have left my personal shorthand in the electronic manuscript, so any entry preceded by . means that I have not yet checked the original citation for accuracy. Although I have chosen to put this list of species names and authors on the Web I have not included the bibliography from which it derives. Please respect the fact that I have decided to share this effort by placing it on the Web for distribution and cite it as above when you use it.


Carlton, J. T. and C. E. Mills, 1999. Preserving living marine resources: havens on the high seas. pp. 3-8 In University of Washington School of Marine Affairs, 25th Anniversary Public Program Proceedings, Seattle, May 7-8, 1998 (W.S. Wooster and W.T. Burke, eds). School of Marine Affairs, University of Washington, Seattle.

In the context of the close of the 20th century and an increasingly apparent deterioration of the marine environment, we urge that it is time to get serious about effective ocean stewardship. The tradition of freedom of the high seas has its roots in an era when there were too few people to violate the oceans, but in hindsight that era may have ended nearly 150 years ago with the increase of global whaling. Man's effect on the oceans is evident nearly everywhere as our ability and interest in harvesting ocean resources increases steadily. Yet our understanding of the biodiversity of the ocean in terms of its organisms, habitats, communities and ecosystems is stymied by a system that no longer values natural history, biogeography and systematics. The loss of genetic diversity, habitat diversity, or even species diversity in the seas in incalculable. Carlton and Mills reiterate our proposal for havens on the high seas, marine protected areas in the international waters of the open ocean, as no-take, no-depository regions for the protection of living resources. Although the "right" fish management policies should be able to accomplish the same goals as open ocean reserves in maintaining or returning fish, invertebrate, and marine mammal populations to sustainable vigor, it is not clear to the authors that there is either the ecological understanding or the collective political will to protect these populations through management rather than no-touch reserves, nor is it evident that fisheries management solutions would be any easier or faster to implement than setting up a system of reserves. The text of the speech resulting in this paper can be read here.

Copies of the (106 page) 25th Anniversary Proceedings can be ordered from the School of Marine Affairs, University of Washington, Seattle WA 98195 or UWSMA@u.washington.edu.


Boero, F. and C. E. Mills, 1999. Hydrozoan people come together. Trends in Ecology and Evolution, 14: 127-128.

This is a news and commentary article about the Fourth Workshop of the Hydrozoan Society, held at the Bodega Marine Laboratory in central California for two weeks in late September, 1998. Fifty-four people attended, from sixteen countries. Forty-four oral presentations and six posters covered various aspects of the biology of the hydrozoa and occupied most of the morning time. Afternoons were spent in (ten) roundtable discussions of new and/or controversial topics and doing field and lab work. Some of the interesting research results are reported, highlighting the breadth of topics explored during this unusual workshop. **PDF file**

An important cooperative idea that coalesced during the meeting is the Project Hydrozoa, suggested by Bernd Schierwater. This comprehensive project will allow scientists from all over the world to plug their work into a grand scheme in which 50­100 selected species, widely distributed throughout the Class Hydrozoa, would form one axis of a grand Data Availability Matrix (DAM), including columns with life history characteristics, molecular sequences for several genes, nematocyst complement, polyp and medusa morphologies, development, literature citations, and other data. Most scientists at the meeting committed to making a special effort to fill in cells in the matrix, thus building an unprecedented web-accessible database from which to answer phylogenetic and evolutionary questions.


Cohen, A., C. Mills, H. Berry, M. Wonham, B. Bingham, B. Bookheim, J. Carlton, J. Chapman, J. Cordell, L. Harris, T. Klinger, A. Kohn, C. Lambert, G. Lambert, K. Li, D. Secord and J. Toft, November 1998. Report of the Puget Sound Expedition, September 8-16, 1998: a Rapid Assessment survey of non-indigenous species in the shallow waters of Puget Sound. Washington State Department of Natural Resources, Olympia, Washington, 37 pages.

This is a Washington State technical report (gray literature) on a 1998 field survey for nonindiginous marine species in Puget Sound, the inland marine waters of Washington. A team of about 20 scientists from universities, a museum, and state and local governments visited 23 marinas (our primary sites) and another 9 secondary sites to inventory the flora and fauna. In addition to over 450 native plants and invertebrates, we collected and identified 39 non-indigenous species in Puget Sound, as well as an additional 23 species of uncertain (cryptogenic) origin that are also likely to be introduced species in our marine waters. This report lists those nonindigenous and cryptogenic species, gives a full description of our collection techniques and the sites visited, and makes some comparisons with findings by similar expeditions (involving some of the same scientists) carried out in San Francisco Bay in recent years.

**PDF file** or **Download the PDF file here.** Paper copies of this report may still be available from Washington State DNR . Contact the Nearshore Habitat Program, Aquatic Resources Division, Washington State Department of Natural Resources, 1111 Washington Street SE, PO Box 47027, Olympia, Washington, 98504-7027; telephone 360-902-1100. Some additional information about the Puget Sound Expedition is also available on the web.


Wrobel, D. and C. Mills, 1998 - Second Printing with corrections 2003. Pacific Coast Pelagic Invertebrates - A Guide to the Common Gelatinous Animals. Sea Challengers and the Monterey Bay Aquarium, Monterey, California, iv plus 108 pp.

This book is an identification guide to 160 species of hydromedusae, siphonophores, scyphomedusae, ctenophores, gelatinous molluscs and pelagic tunicates that occur along the west coast of North America from Alaska to Baja California. Each species is individually illustrated with a photograph that is accompanied by a detailed description, range and habitat notes, and natural history information. A final section includes the derivations of the scientific names of species included, a taxonomic classification of these species, and a checklist by habitat of all gelatinous zooplankton reported from the west coast. Most species included are coastal, but there are also many oceanic and deep-sea species likely to be collected in offshore plankton tows or midwater trawls. Naturalists, scuba divers, boaters, teachers, students and scientists should find this guidebook useful to identify and learn about many of the animals called "gelatinous zooplankton" that may be observed along the Pacific coast. Available at various bookstores including Sea Challengers.com and the Monterey Bay Aquarium Bookstore.
See Acta Errata; errors in this book have been corrected in the 2003 Second Printing.


Mills, C. E. and J. T. Carlton, 1998. Rationale for a system of international reserves for the open ocean. Conservation Biology, 12: 244-247.

There appears to have been little high-level consideration given to the concept of marine reserves in open-ocean ecosystems, whereas a large number of protected areas for coastal marine and estuarine ecosystems have been or are now being developed around the world. We propose that, given the rapidly rising pressures on the oceans due to human overpopulation and associated resource extraction, ocean conservation and management in the 21st century should include a system of marine reserves for the open ocean. We define "open ocean" for the present purposes as including both the water column (the pelagic realm) and the sea floor (the benthic realm) in international waters, that is, beyond 200 miles (320 kilometers) from a nation's coastline.

We suggest that a system of international open ocean reserves would be practical and that the benefits of such a system would be of global importance. There are compelling reasons from the points of view of both conservation biology and oceanography to set aside areas of the mid-ocean, regions of rich biodiversity, as marine reserves. Although it might be argued that we don't know enough yet to chose the best locations or optimal sizes for open ocean reserves, we maintain that refuges should be established soon rather than holding out for more data. Making some decisions now will buy time for the oceanic species likely to be most impacted by man's activities.
**PDF file**

This idea was first aired as a talk at the annual meeting of the Society for Conservation Biology in June 1997 in Victoria, British Columbia.
See Acta Errata.


Mills, C.E. Internet 1998-present. Phylum Ctenophora: list of all valid species names.
Electronic internet document, available at http://faculty.washington.edu/cemills/Ctenolist.html. Published by the author, web page established March 1998, see web page for most recent update.

This electronic document consists of a list of all ctenophore classes, orders, families, genera and species and their authors and dates that I have found in a rather extensive search of the literature; links are included to ctenophore images (by species) located elsewhere on the web. This list is still an ongoing work and is subject to modification at any time; I welcome any additions or corrections that anyone may wish to submit. In many cases, I have listed older synonyms to good species names in parentheses on the line following. There are probably many other synonyms in this list of names (the genus Beroe, for instance, has many names that are likely ultimately to be synonomized in future studies). In order to be true to its in-progress nature, I have left my personal shorthand in the electronic manuscript, so any entry preceded by . means that I have not yet checked the original citation for accuracy. Although I have chosen to put this list of species names and authors on the Web I have not included the bibliography from which it derives at this time, in order to save space. Please respect the fact that I have decided to share this effort by placing it on the Web for distribution and cite it as above when you use it.

Boero, F. and C. E. Mills, 1997. Agricultural versus ethological oceanography. Trends in Ecology and Evolution, 12: 208-209.

This is a news and commentary article about the special sessions on gelatinous zooplankton at the 1997 annual meeting of the American Society of Limnology and Oceanography at Santa Fe, New Mexico. Thirty papers or posters covered various aspects of the biology of both herbivorous and carnivorous gelatinous zooplankton; this portion of the meeting was especially well attended partly because it included a tribute to William and Peggy Hamner, pioneers in ethological oceanography who began the practice of blue-water diving and in situ observation of gelatinous zooplankton in the late sixties. Some of the interesting new research results reported at the meeting are mentioned. Although the broad separation between students of "classical" crustacean zooplankton and those studying gelatinous zooplankton was highlighted even by schedule conflicts between these two seemingly inextricably-related topics, the gelatinous sessions helped dramatize the fact that in spite of growing interest in modeling processes in the ocean, it continues to be timely and illuminating to go back and LOOK at the organisms. Such observations continue to be helpful in our understanding of how the ocean works. **PDF file**


Mills, C.E. 1996. Additions and corrections to the keys to Hydromedusae, Hydroid polyps, Siphonophora, Stauromedusan Scyphozoa, Actiniaria, and Ctenophora. pp. 487-491 (authorship of these corrections is not given within the text) In Marine Invertebrates of the Pacific Northwest, with additions and corrections (E.N. Kozloff and L.H. Price, eds.). University of Washington Press, Seattle.

These pages include revisions to the Keys published in 1987 (see below) for marine invertebrates of the NE Pacific, covering coastal species that might be encountered between southern Oregon and the Queen Charlotte Islands, British Columbia. A number of small changes are found in these revisions including basic corrections, name changes, and the addition of new species. Major additions include a revised key to Obelia polyps (3 species), a new key to the Stauromedusae (6 species), a new key to Beroe ctenophores (5 species), and 13 new reference citations of local taxonomic significance.


Mills, C.E., P.R. Pugh, G.R. Harbison and S.H.D. Haddock, 1996. Medusae, siphonophores and ctenophores of the Alborán Sea, south western Mediterranean. Scientia Marina, 60: 145-163.

Fifty-eight species of planktonic Cnidaria and Ctenophora were observed and collected in the Alborán Sea (western Mediterranean) during a cruise in April 1991 on the RV Seward Johnson. Eleven stations were sampled 10 to 21 nautical miles off the north coast of Morocco between the Strait of Gibraltar and the Cap de Trois Fourches: 26 dives using the manned submersible Johnson-Sea-Link I were made to bottom depths of 370-850 m, and at 5 of the same stations we made a total of 7 blue-water SCUBA dives from the surface to about 15 m. Twelve species of hydroidomedusae, 18 species of siphonophores, 6 species of scyphomedusae, and 22 species of ctenophores were collected. The most numerous species seen from the submersible in deep water included Solmissus albescens, Haliscera conica, Forskalia (?)formosa, Lensia conoidea, Abylopsis tetragona, Paraphyllina ransoni, Periphylla periphylla, Euplokamis stationis, Bathocyroe fosteri, Bolinopsis infundibulum, an undescribed cydippid ctenophore, and an undescribed lobate ctenophore. Species that were most numerous near the surface were Pandea conica, Solmaris leucostyla, Nanomia bijuga, Haeckelia beehleri, Pleurobrachia rhodopis, Bolinopsis vitrea, Ocyropsis maculata immaculata, Beroe ovata, and an undescribed cydippid ctenophore. Advantages of using a submersible for this study included the ability to collect in perfect condition fragile forms like siphonophores and ctenophores that fall apart when collected in nets, the possibility to obtain a realistic image of small-scale distribution throughout the water column and to sample plankton very close to the sea floor. **PDF file**


Mills, C.E. 1995. Ctenophora. In Checklist delle specie della fauna italiana, Vol. 3, pp 3,5, 32-38. (A. Minelli, S. Ruffo, S. La Posta, editors). Edizioni Calderini, Bologna.

This publication lists 24 species of planktonic ctenophores that have been collected in Italian waters and another 8 species that have been collected just outside of Italy in the French Ligurian Sea and could be expected to be found in Italian waters. No benthic ctenophores have been reported in Italy. The study of ctenophores in Italian waters is recorded in the scientific literature over the past nearly 150 years. The majority of Italian ctenophore collections have been made at either Naples or Messina. Accordingly, nearly all of the observations listed here for the Thyrrenian Sea were made in the Bay of Naples. As the Strait of Messina is between the Thyrrenian Sea and the Ionian Sea, I have chosen to list all of the Messina observations under the Ionian Sea - these are perhaps the only recorded ctenophore observations in the Ionian Sea. Because the literature for ctenophore taxonomy is so scattered both in time and space, I have included a number of synonyms in the checklist so that the non-specialist can better interpret his collection.


Mills, C.E. 1995. Medusae, siphonophores, and ctenophores as planktivorous predators in changing global ecosystems. ICES Journal of Marine Science, 52: 575-581.

Medusae, siphonophores, and ctenophores are planktivorous predators operating at higher trophic levels in marine ecosystems of a wide range of productivity. It has been hypothesized that high-productivity ecosystems such as areas of upwelling tend towards food chains dominated by larger phytoplankton, large copepods, and ultimately many species of fish rather than gelatinous predators; ecosystems with lower productivity are characterized by small flagellate phytoplankton, small copepods, and ultimately numerous medusae and ctenophores. Evidence is provided that medusae, siphonophores, and ctenophores are actually important predators in both sorts of planktonic ecosystems, although uneven reporting in the literature may be cause for underestimates of the importance of these carnivores in some systems. As world fisheries begin to experience serious declines, it is relevant to recognize that the carnivorous "jellyfishes" are ubiquitous and are thus opportunistically positioned to utilize secondary production that is ordinarily consumed by fish. **PDF file**


Mills, C.E. and F. Sommer, 1995. Invertebrate introductions in marine habitats: two species of hydromedusae (Cnidaria) native to the Black Sea, Maeotias inexspectata and Blackfordia virginica, invade San Francisco Bay. Marine Biology, 122: 279-288.

The hydrozoans Maeotias inexspectata Ostroumoff, 1896 and Blackfordia virginica Mayer, 1910, believed to be native to the Black Sea (i.e. Sarmatic) and resident in a variety of estuarine habitats worldwide, were found as introduced species in the Petaluma River and Napa River, California, in 1992 and 1993. These rivers are mostly-estuarine tributaries that flow into north San Francisco Bay. Both species appeared to be well-established in this brackish water habitat. Salinities at the collection sites were about 11 during the summer, rising to nearly 20 in the early autumn and falling to near 0 in the winter. Large numbers of all sizes of both species of medusae were observed and collected, indicating that the hydroid stages of the life cycles of the two are also well-established in these rivers. In the Petaluma River, populations of both species were at maximum in late July, with numbers of individuals declining through August and into September; the Napa River was sampled only in October and at that time only B. virginica was found. Examination of full guts of M. inexspectata and B. virginica medusae revealed that both species had fed nearly exclusively on small crustaceans, principally barnacle nauplii, copepods and their eggs and nauplii, and crab zoea larvae (M. inexspectata only). All the M. inexspectata medusae were males, indicating that the population has likely developed from the introduction of perhaps only a single male polyp or polyp bud. In spite of its inability to reproduce sexually, this population appears to be maintained by the prodigious ability of the polyp to bud and reproduce asexually and is fully capable of invading additional low salinity habitats from its present Petaluma River site. Male and female B. virginica medusae were collected in both the Petaluma River and the Napa River, indicating that B. virginica may have been introduced by either the polyp or medusa stage (or both), but that multiple individuals (of both sexes) must have arrived from another port in one or more invasions. As indicated for M. inexspectata, the B. virginica population will also likely seed new populations in San Francisco Bay and elsewhere. Based on its cnidome as well as the morphology of both medusa and polyp, M. inexspectata has been reclassified by moving it from the family Olindiidae, Limnomedusae to the family Moerisiidae, Anthomedusae. **PDF file**
See Acta Errata.


Mills, C.E. 1994. Seasonal swimming of sexually mature benthic opisthobranch molluscs (Melibe leonina and Gastropteron pacificum) may augment population dispersal. pp. 313-319 In Reproduction and Development of Marine Invertebrates. (W.H. Wilson Jr., S.A. Stricker, G.L. Shinn, editors). Johns Hopkins University Press, Baltimore. (Christopher G. Reed Memorial Symposium).

Although adults of the opisthobranch gastropods Melibe leonina and Gastropteron pacificum are primarily benthic crawlers, they are also capable swimmers. Long-term observations (13-15 years) of plankton in surface waters at Friday Harbor, Washington, reveal that swimming of adult animals in these species is highly seasonal. For M. leonina, which appears to have no permanent populations within at least 2 km of the study site, nearly all swimming adults were observed in surface waters between September and March. Most swimming G. pacificum, with a resident population on the sloping mud-sand bottom 5-18 m immediately below the observation site, were also seen near the surface between September and February. Swimming individuals from both species were sexually mature, or nearly so, as shown by their ability to reproduce in the laboratory after collection. Although both species have planktonic veliger larvae, commonly considered to be their chief agents for dispersal, these observations suggest the additional importance of seasonally swimming adults in achieving population movements. **PDF file**


Mills, C.E. 1993. Natural mortality in NE Pacific coastal hydromedusae: grazing predation, wound healing and senescence. Bulletin of Marine Science, 53: 194-203. (Proceedings of the Zooplankton Ecology Symposium)

Hydromedusae appear in the coastal plankton during defined species-specific periods. In a predictable succession, some species appear shortly after the spring plankton bloom begins, and others follow as ecological conditions continue to change. Most species also have well-defined seasonal terminations. This study explores the programs of mortality in the field other than whole-animal predation of five abundant species of hydromedusae in the San Juan Archipelago, north of Puget Sound in Washington State.

Living specimens were regularly hand-collected and examined for injuries, disease, general deterioration, evidence of damage by parasites or symbionts, and for gut fullness. Young spring medusae of most hydrozoan species were in excellent physical condition. The proportion of damaged individuals increased with time throughout the season. The nature and source of this damage varied according to the species of hydromedusa. The large, long-lived species Aequorea victoria and Mitrocoma cellularia showed high amounts of grazing damage, caused mostly by hyperiid amphipods and parasitic larval sea anemones, whose negative effects accumulate late in the season. The shorter-lived species Clytia gregaria and Mitrocomella polydiademata showed lower overall incidence of damage than species with long-lived individuals, and were assumed to be removed largely by whole animal (rather than grazing) predation. Senescence was seen to be the primary factor only in the demise of the population of Gonionemus vertens. **PDF file**


Brinckmann-Voss, A., D.M. Lickey and C.E. Mills, 1993. Rhysia fletcheri (Cnidaria, Hydrozoa, Rhysiidae), a new species of colonial hydroid from Vancouver Island (British Columbia, Canada) and the San Juan Archipelago (Washington, U.S.A.). Canadian Journal of Zoology, 71: 401-406.

A new species of colonial athecate hydroid, Rhysia fletcheri, is described from Vancouver Island, British Columbia, Canada, and from Friday Harbor, Washington, U.S.A. Its relationship to Rhysia autumnalis Brinckmann from the Mediterranean and Rhysia halecii (Hickson and Gravely) from the Antarctic and Japan is discussed. Rhysia fletcheri differs from Rhysia autumnalis and Rhysia halecii in the gastrozooid having distinctive cnidocyst clusters on its hypostome and few, thick tentacles. Most of its female gonozooids have no tentacles. Colonies of R. fletcheri are without dactylozooids. The majority of R. fletcheri colonies are found growing on large barnacles or among the hydrorhiza of large thecate hydrozoans. Rhysia fletcheri occurs in relatively sheltered waters of the San Juan Islands and on the exposed rocky coast of southern Vancouver Island. **PDF file**
A full version of this paper, with additional color photographs is posted here on the web.


Marliave, J.B. and C.E. Mills, 1993. Piggyback riding by pandalid shrimp larvae on hydromedusae. Canadian Journal of Zoology, 71: 257-263.

Pandalid shrimp larvae in protected Northeast Pacific marine waters are opportunistic hitchhikers, riding piggyback on jellyfish having a bell diameter similar to the leg span of the shrimp. Ridden medusae pulsed faster and for longer periods than unridden ones. Ridden medusae rested or fed only one-third as long as they swam, whereas the resting and feeding bouts of unridden medusae normally lasted twice as long as swimming bouts. The shrimp neither damage the jellyfish nor take food from them, but many of the ridden jellyfish apparently die, perhaps because of increased energetic load. We document occurrences of at least 6 species of pandalid shrimp larvae riding on 7 species of hydromedusae in the field, together with observations of the behavior of wild-caught medusae and riders in laboratory tanks.


Mackie, G.O., C.E. Mills and C.L. Singla, 1992. Giant axons and escape swimming in Euplokamis dunlapae (Ctenophora: Cydippida). Biological Bulletin, 182: 248-256.

Euplokamis dunlapae responds to anterior stimulation by reversing the beat direction of its comb plate cilia and swimming rapidly backwards. It responds to posterior stimulation by swimming forwards at an accelerated rate. Video playback and laser monitoring were used to analyze changes in the pattern of ciliary beating, while electrical actiivity was recorded extracellularly. Escape responses occur with latencies of less than 150 ms and involve greatly increased ciliary beat frequencies. Giant axons run longitudinally along each of the eight comb rows, as shown by optical and electron microscopy. They form chains of overlapping neurons, with diameters of about 12 µm in life, and conducting at over 50 cm x s-1 as recorded with an extracellular electrode placed directly over the chain. The giant neurons are synaptically linked with smaller neurites of the general ectodermal nerve plexus, with each other, and with the ciliated cells of the comb plates. They appear to constitute a single system mediating rapid conduction of signals in either direction, but a full analysis was not attempted for lack of sufficient material. Electrophysiological examination of two other ctenophores (Pleurobrachia and Beroe) gives no indication of rapid conduction pathways, and these forms probably lack giant axons. **PDF file**


Mills, C.E. 1991. Deep-Sea Fauna: Narcomedusae. pp. 103-105 In McGraw-Hill 1992 Yearbook of Science and Technology. McGraw-Hill Book Company, New York.

Recent research on deep-sea fauna has included investigations of a group of oceanic jellyfishes, the narcomedusae. All narcomedusae are holoplanktonic; a few species live in coastal waters, but most occur in the open ocean. Oceanic species occur from the upper mixed later to great depths, where they may be very numerous. Most narcomedusae apparently feed primarily on gelatinous zooplankton; some are active vertical migrators, moving up to hundreds of meters through the water column on a daily program. Narcomedusae do not have polyps; their entire life cycle takes place in the water column and most probably live less than one year.


Larson, R.J., C.E. Mills and G.R. Harbison, 1991. Western Atlantic midwater hydrozoan and scyphozoan medusae: in situ studies using manned submersibles. pp. 311-317 In Coelenterate Biology: Recent Research on Cnidaria and Ctenophora. (R.B. Williams, P.F.S. Cornelius, R.G. Hughes, E.A. Robson, editors). Hydrobiologia, 216/217: 311-317.

Little is known about the biology and ecology of mesopelagic medusae. In part, this is because midwater trawls are used to collect fragile medusae and other gelatinous macroplankton. Additionally, nets cannot provide data on behavior and on biotic associations. In situ observations on northwestern Atlantic midwater medusae made using the Johnson-Sea-Link submersibles are reported. Included are depth and temperature ranges, notes on pigments, locomotory behavior; and notes on prey and predators.


Mills, C.E. and N. McLean, 1991. Ectoparasitism by a dinoflagellate (Dinoflagellata: Oodinidae) on 5 ctenophores (Ctenophora) and a hydromedusa (Cnidaria). Diseases of Aquatic Organisms, 10: 211-216.

Oodinium sp., an ectoparasitic oodinid dinoflagellate that closely resembles Oodinium jordani McLean & Nielsen, 1989 described from Sagitta elegans Verrill, 1873 (Phylum Chaetognatha), has been seen to parasitize Beroe abyssicola Mortensen, 1927, Bolinopsis ?infundibulum (O. F. Müller, 1776), Euplokamis dunlapae Mills, 1987, Dryodora glandiformis (Mertens, 1833), and Pleurobrachia bachei A. Agassiz, 1860, which represent 3 orders of the Phylum Ctenophora, and the hydromedusa Euphysa sp. (Phylum Cnidaria) in marine waters of the San Juan Archipelago, Washington State, U. S. A. Up to several hundred trophozoites may be found on a single ctenophore, although most ctenophore hosts carry less than 50; the hydromedusa never carried more than 4. The parasites occurred on their ctenophore and medusan hosts from late October through early April, and not in the warmer months. These are the first reported instances of parasitism by a dinoflagellate on the Ctenophora, and by an Oodinium on the Cnidaria. **PDF file**


Carré, D., C. Carré and C.E. Mills, 1989. Novel cnidocysts of narcomedusae and a medusivorous ctenophore, and confirmation of kleptocnidism. Tissue and Cell, 21: 723-734.

Cnidocysts have been examined from the tentacles of the ctenophore Haeckelia rubra (Euchlora rubra) and five species of hydrozoan narcomedusae (Solmundella bitentaculata, Aegina citrea, Solmissus marshalli, Solmissus albescens, and Cunina sp.) using TEM, both in sections and by firing whole cnidocysts onto EM grids. The study revealed that these apotrichous isorhiza cnidocysts have a novel morphology in which the intracapsular inverted tubule has five circumferential pleats when viewed in transverse section, rather than the usual three pleats. Accordingly, the definition of helicoptychoneme cnidocysts has been broadened to include both the usual three-pleated cnidocysts and these new five-pleated cnidocysts. In general, apotrichous isorhizas have subspherical capsules with a thick, bilayered wall, whose interior is nearly filled with the regularly coiled, helically folded, five-pleated inverted tubule. Upon discharge, the everted tubule is several mm long and the five circumferential pleats become manifested as five helical rows of spines running up the tubule, which has three morphologically different segments. The very short basal segment is devoid of ornamentation; the remaining proximal portion is characterized by five spirals of uniform, closely packed short spines; the long distal portion is characterized by a single spiral of regularly spaced large spines that derive from all five spirals-the five spirals are otherwise demarcated in the distal portion by 'scales' that are visible only with the electron microscope. **PDF file**


Larson, R.J., C.E. Mills and G.R. Harbison, 1989. In situ foraging and feeding behavior of Narcomedusae (Cnidaria, Hydrozoa)Journal of the Marine Biological Association of the United Kingdom, 69: 785-794.

Narcomedusae are a small and mostly oceanic group of hydromedusae whose tentacle morphology and comportment sets them off behaviourally and perhaps ecologically from most other medusae. Their tentacles are relatively few in number (2-40), stiff, and non-contractile, with points of insertion located well above the bell margin. Eleven species representing eight narcomedusan genera (Aegina, Aeginura, an undescribed aeginid, Cunina, Pegantha, Solmaris, Solmissus, and Solmundella) were observed and collected in situ in the N.W. Atlantic, Arctic and Antarctic, using scuba and manned submersibles. In life, the tentacles of narcomedusae are nearly always held upwards over the bell or projected laterally. The major prey were other gelatinous zooplankton, especially salps and doliolids. In the laboratory, these relatively large prey were caught on the tentacles, which bend inward and coil at the tips to bring food to the mouth. By extending the tentacles perpendicular to the swimming path, these medusae achieve a relatively large encounter area, thus increasing the probability of contact with prey.


Laval, P., J.-C.Braconnot, C. Carré, J. Goy, P. Morand and C.E. Mills, 1989. Small-scale distribution of macroplankton and micronekton in the Ligurian Sea (Mediterranean Sea) as observed from the manned submersible Cyana.. Journal of Plankton Research, 11: 665-685.

A series of eight submersible dives (the MIGRAGEL I cruise) was made during late April 1986 using the French submersible Cyana to investigate macrozooplankton in the upper 400-700 m of the water column. Paired day and night dives were made at stations 3, 6, 13, and 23 nautical miles off Cape Ferrat, near Villefranche-sur-Mer, France; the distances represent different areas in the frontal system of the Ligurian Sea. Detailed day/night vertical distribution data are shown for the most abundant species; these include the narcomedusa Solmissus albescens, teleost fish Cyclothone spp., small appendicularians (primarily Oikopleura albicans), large appendicularians (an undescribed oikopleurid), diphyid siphonophores (mostly Chelophyes appendiculata) and an abundant lobate ctenophore. Salps, pyrosomes, amphipods (Phronima sedentaria), pteropods(Cavolinia inflexa), macroscopic 'star-like' protozoa and marine snow are also briefly discussed. The coastal zone was dominated by small appendicularians in the upper layers, with other filter feeders including large appendicularians in deeper water - these just above a non-migratory population of carnivorous Cyclothone. The carnivorous medusa Solmissus albescens moved throughout the upper 600 m in the course of its diel vertical migration. Offshore, carnivores were dominant throughout the water column, with numerous diphyid siphonophores in the upper layers, and Cyclothone, lobate ctenophores and macroprotozoa abundant in deeper water. Solmissus was also present, and was more numerous offshore than in the coastal zone.


Larson, R.J., G.R. Harbison, P.R. Pugh, J.A. Janssen, R.H. Gibbs, J.E. Craddock, C.E. Mills, R.L. Miller and R.W. Gilmer, 1988. Midwater community studies off New England using the Johnson Sea-Link submersibles. NOAA National Undersea Research Program Research Report 88-4: 265-281.

The midwater community off New England was studied using manned submersibles. Twenty-three dives were made in three submarine canyons SE of Woods Hole in 800 m of water. We found a diverse community present. Gelatinous zooplankton (medusae, siphonophores and ctenophores) were represented by 38 species, several are undescribed. The vertical distributions of most were determined and it was discovered that they were mostly mesopelagic (occurring below 400 m). Ctenophores were both diverse and numerous in contradiction to the results of studies using nets. The siphonophore Nanomia cara, which showed evidence of a 150 m diel vertical migration, was most abundant. Crustacean micronekton consisted mostly of Meganyctiphones norvegica, Sergestes sp., and Themisto gaudichaudii. These species all vertically migrated 100 m or more and were sometimes very numerous in midwater strata or near the bottom. Midwater fishes were found in the mesopelagic, but some migrated into the upper 100 m at night. It is concluded that predation by visually orienting predators in surface waters may be the primary factor which determines vertical distributions. Nevertheless, the mesopelagic is not a good refuge from predators because there are large numbers of gelatinous predators there.


Mills, C.E. and J. Goy, 1988. In situ observations of the behavior of mesopelagic Solmissus narcomedusae (Cnidaria, Hydrozoa). Bulletin of Marine Science (Proceedings of the Zooplankton Behavior Symposium), 43: 739-751.

Solmissus albescens is the most numerous medusa in the mesopelagic western Mediterranean. This endemic species undergoes a nocturnal vertical migration from a depth of 400-700 m to the upper 100 m. In situ observations of S. albescens reported here were made during 10 dives using the French submersible CYANA in 1985-1986 in conjunction with simultaneous conventional plankton sampling, and are combined here with published observations by earlier French submersible users for completeness. The hundreds of 2-5 cm diameter S. albescens seen from the CYANA were almost always actively swimming regardless of time of day, with pulsation frequencies between 1.3 and 2.0 Hz. Swimming becomes directional at dawn and at dusk and the speed of upward and downward migrations appears to be the same, approximately 100 m per hour as estimated from in situ point observations and from population depth distribution at different times of late afternoon, evening and morning. Vertical migration appears to be conducted solely by swimming without need for changes in buoyancy. S. albescens can hold its non-extensible tentacles directly above its bell, curved laterally outward, or directed downward. Unlike many other hydromedusae, S. albescens swims and feeds simultaneously. Although all net-collected Solmissus had empty guts both during the day and at night, from the submersible we saw S. albescens feeding on non-migratory epipelagic Cavolinia pteropods at night. One S. albescens during the day was seen capturing a lobate ctenophore, but all other daytime observations indicated empty guts. Solmissus and other narcomedusae may be limited to feeding on soft-bodied prey by the type of nematocysts on their tentacles (apotrichous isorhizas). S. marshalli has also been observed in situ, from the SEA LINK II and PISCES IV submersibles. In comparison to S. albescens, this cosmopolitan mesopelagic species has slower swimming speed (0.6-0.7 Hz), frequent periods of quiescence, and no long-range diel migrations.


Purcell, J.E. and C.E. Mills, 1988. The correlation between nematocyst types and diets in pelagic Hydrozoa. pp. 463-485 In The Biology of Nematocysts. (D.A. Hessinger and H.M. Lenhoff, editors). Academic Press, Orlando.

Among the pelagic hydrozoans, which include the siphonophores, hydromedusae, and velellids (chondrophores), members of some taxonomic subgroups exclusively or primarily consume soft-bodied prey, while others primarily consume hard-bodied (crustacean) prey. The dietary differences are related to the types of nematocysts in the tentacles of these hydrozoans. The predators of crustaceans are the calycophore and physonect siphonophores, Anthomedusae (except the family Pandeidae), Limnomedusae, and Trachymedusae. These groups possess 2 to 5 types of nematocysts, including rhopalonemes (acrophores, anacrophores, and desmonemes) which adhere to and entangle prey, and stenoteles, microbasic euryteles, or microbasic mastigophores, which can penetrate crustacean exoskeleton. Adhesion of nematocyst tubules to prey surfaces appears to be important in capture of crustaceans by hydrozoans. Predators of soft-bodied plankton include the cystonect siphonophores, Apolemia uvaria (Physonectae), pandeid Anthomedusae, Leptomedusae, and Narcomedusae. Their cnidoms usually contain one type or one predominant type of nematocyst, primarily isorhizas, mastigophores, or other types often unique to them, that penetrate the soft prey tissues, but they lack surface-adhering nematocyst types.

Herein, we briefly review earlier work on the diets and nematocysts of the Siphonophora, and present new data on the diets and nematocysts of the diverse hydromedusan species from the Strait of Georgia region, Northeast Pacific. **PDF file**


Mackie, G.O., C.E. Mills and C.L. Singla, 1988. Structure and function of the prehensile tentilla of Euplokamis (Ctenophora, Cydippida). Zoomorphology, 107: 319-337.

Euplokamis has coiled tentilla on its tentacles, which can be discharged, flicking out at high velocity, when triggered by contact with prey. The tentillum adheres to prey by means of numerous colloblasts. Discharge, which takes 40-60 ms, is accomplished by contraction of striated muscles, found only in this genus among the Ctenophora. Restoration of the coiled state is attributable to passive, elastic components of the mesogloea. Rows of "boxes" (fluid-filled compartments) along the sides of the tentillum appear to stiffen the structure so that it does not collapse, kink or buckle during discharge. Smooth muscle fibres present in the tentillum may help pull the tentillum tight after prey have been captured.

In addition to the rapid discharge response, the tentillum can perform slower, spontaneous, rhythmic movements which, it is suggested, resemble the wriggling of a planktonic worm, enabling the tentillum to function as a lure. These movements appear to be executed by contraction of two sets of myofilament-packed cells which differ in several important respects from conventional smooth muscle. They belong to a novel and distinct cytological subset ("inner-ring cells"), other members of which are packed with microtubules and seem to be involved in secondary structuring of the collagenous component of the mesogloea.

Study of tentilla in different stages of development shows that the striated muscle fibres, originally nucleated, become enucleate as they differentiate and that the colloblasts form in association with accessory cells, as proposed by K.C. Schneider and G. Benwitz. The refractive granules which adhere to the outside of all mature colloblasts derive from these accessory cells. the colloblast nucleus undergoes changes during development suggestive of progressive loss of its role in transcription and protein sythesis, but it remains intact, contrary to statements in the literature. The tentillum of Euplokamis can be regarded as a true food-capturing organ and it is probably the most highly developed organ in the phylum. **PDF file**


Mills, C.E. 1987. Revised classification of the genus Euplokamis Chun, 1880 (Ctenophora: Cydippida: Euplokamidae n. fam.), with a description of the new species Euplokamis dunlapae. Canadian Journal of Zoology, 65: 2661-2668.

The cydippid ctenophore Euplokamis dunlapae n. sp. from fjords and inlets in British Columbia and Washington State is described and illustrated. The monotypic new family Euplokamidae has been erected to accommodate this genus, which is characterized by tentacle side branches containing striated muscle, unique in the phylum Ctenophora. These side branches are tightly coiled when at rest, but extend very rapidly during prey capture. Feeding and swimming behavior and larval morphology are discussed. A review of the literature has led to a reassessment of the affinities of several cydippid ctenophores and a dichotomous key is included for the identification of five species (see Note added in Proof) in the genus Euplokamis.
See Acta Errata.


Mills, C.E. and M.F. Strathmann, 1987. Phylum Cnidaria, Class Hydrozoa. pp. 44-71 In Reproduction and Development of Marine Invertebrates of the Northern Pacific Coast (M.F. Strathmann, ed.) University of Washington Press, Seattle and London.

This chapter includes a general summary of reproduction and development in marine Hydrozoa, followed by specific practical information on the use of material found along the northern Pacific Coast of the United States and Canada. Topics covered include identification, collection and maintenance, collecting newly released medusae, collecting gametes, insemination, culture set-ups, isolation or fusion of embryo parts, vital staining, dissociation and reaggregation of blastomeres, and centrifugation of eggs. This section is followed by specific information on selected local species including 17 Anthomedusae or athecate hydroids, 14 Leptomedusae or thecate hydroids, 2 species of Limnomedusae, one (Trachyline) Narcomedusa, one stylasterine "hydrocoral", and 2 species of siphonophores. An extensive list of references containing information on reproduction and development in the Hydrozoa concludes the chapter.


Mills, C.E. 1987. Keys to the Hydrozoan Medusae (pp. 32-44), Siphonophora (pp. 62-65), Scyphozoa: Semaeostomae (pp. 65-67), and Ctenophora (pp. 79-81). In Marine Invertebrates of the Pacific Northwest (E.N. Kozloff and L.H. Price, eds.) University of Washington Press, Seattle and London.

These publications represent single-authored chapters in a book of keys for marine invertebrates of the NE Pacific. The keys are meant to cover coastal species that might be encountered between southern Oregon and the Queen Charlotte Islands, British Columbia. Separate dichotomous keys are provided for 63 species of hydromedusae, 12 species of siphonophores, 6 species of semaeostome scyphomedusae, and for 11 species of ctenophores. Illustrations are provided for 22 of the hydromedusae, 2 siphonophores, 3 scyphomedusae, and 2 of the ctenophores.


Mills, C.E. and R.L. Miller, 1987. Key to the Hydroid Polyps. pp. 44-61 In Marine Invertebrates of the Pacific Northwest (E.N. Kozloff and L.H. Price, eds.) University of Washington Press, Seattle and London.

This publication is one chapter in a book of keys for marine invertebrates of the NE Pacific. The keys are meant to cover coastal species that might be encountered between southern Oregon and the Queen Charlotte Islands, British Columbia. The key to hydroid polyps includes members of 28 genera of athecate polyps of which 26 species are identified, 38 genera of thecate polyps of which 6 are identified to species, and 3 species of polyps of Limnomedusae. Thirty-four species of hydroids are illustrated. We wrote this key only because no one more qualified stepped up to do it - it has many problems and can best be described as "better than no key." This key is particularly weak in identifying thecate species, which are poorly known in the region. The hydroid polyps as a group are greatly in need of further study along the entire west coast of North America.


Mills, C.E. 1987. In situ and shipboard studies of living hydromedusae and hydroids: preliminary observations of life cycle adaptations to the open ocean. pp. 197-207 In Modern Trends in the Systematics, Ecology and Evolution of Hydroids and Hydromedusae. (J. Bouillon, F. Boero, F. Cicogna and P.F.S. Cornelius, editors). Clarendon Press, Oxford.

Oceanic hydromedusae were studied on two three-week cruises in the tropical and subtropical Atlantic Ocean. Medusae were individually collected by snorkeling, scuba diving, or from a manned submersible at precisely known locations from the surface to 725 m depth. Specimens were maintained as long as possible on shipboard, for periods of one or two days to two weeks. The observations have been compared with similar collections and laboratory studies in deep temperate coastal fjords in the northeast Pacific and with various reports in the literature.

These in situ observations of oceanic and coastal hydromedusae have provided some interesting insights into life cycles and reproductive capabilities of Hydrozoa. It was predicted that coastal medusae should have alternating life cycles with a benthic hydroid phase and that oceanic medusae should have holoplanktonic life cycles. It was found, however, that surface-dwelling (epipelagic) medusae in both coastal and open ocean areas are mostly Anthomedusae and Leptomedusae with alternating life cycles, and that deep-water medusae are mostly Trachymedusae and Narcomedusae with holoplanktonic life cycles. Preliminary observations also indicate that surface-dwelling open-ocean medusae have a greater capacity for asexual reproduction, including several types of fission, than was previously believed. It appears to be this ability for asexual proliferation, coupled with minor adaptations of the hydroid phase of the life cycle, that has allowed so many 'coastal' forms to successfully colonize the open ocean.


Mills, C.E., R.J. Larson and M.J. Youngbluth, 1987. A new species of coronate scyphomedusa from the Bahamas, Atorella octogonos. Bulletin of Marine Science, 40: 423-427.

Atorella octogonos, a new species of coronate scyphomedusa from the Bahamas, is described based on material collected at approximately 500 m by the manned submersible JOHNSON-SEA LINK II. This medusa is distinct from other Atorella species in having eight gonads, whereas the other known species have four or six gonads. Consideration of this new material along with recent descriptions of Atorella polyps has lead us to conclude that the hexamerous symmetry of this genus was probably derived from a typically tetramerous nausithoid ancestor. Consequently, it is recommended that the genus Atorella be transferred to the family Nausithoidae, to which it appears to be most closely related. **PDF file**


Mills, C.E., G.O. Mackie and C.L. Singla, 1985. Giant nerve axons and escape swimming in Amphogona apicata, with notes on other hydromedusae. Canadian Journal of Zoology, 63: 2221-2224.

The trachyline medusa Amphogona apicata (family Rhopalonematidae) possesses giant axons and other special features previously described in Aglantha digitale and shows similar escape-swimming and slow-swimming responses. A review of the literature and new observations on several trachymedusan species suggest that these locomotory adaptations seem to have evolved only within the hydrozoan family Rhopalonematidae, with the possible exception of members of the related trachymedusan family Ptychogastriidae. **PDF file**


Mills, C.E. 1985. A new hydrozoan Geomackiea zephyrolata gen. nov., sp. nov. (Anthomedusae: Pandeidae) from inland marine waters of British Columbia and Washington State. Canadian Journal of Zoology, 63: 2172-2175.

The hydromedusa Geomackiea zephyrolata gen. nov., sp. nov. is described and illustrated. It has been placed in the subfamily Protiarinae of the family Pandeidae on the basis of its stomach and gonad morphology and the four large perradial tentacles with conical basal bulbs. A new genus has been erected because the medusa is supplied with four broad interradial bulbs, each rimmed by up to eight closely packed solid tentaculae. A total of 29 specimens with bell heights of 0.9-3.5 mm have been collected in the plankton of Saanich Inlet, British Columbia, and Friday Harbor, Washington, between 1978 and 1981. Juvenile as well as adult specimens are described and the cnidome, gametes, seasonal and vertical distributions, and taxonomic affinities within the family Pandeidae are discussed. **PDF file**


Mills, C.E. 1984. Seasonal and vertical distribution of medusae, siphonophores and ctenophores in Saanich Inlet. pp. 77-79 In Proceedings of a multidisciplinary symposium on Saanich Inlet, 2 February 1983. (S.K. Juniper and R.O. Brinkhurst, eds.) Canadian Technical Report of Hydrography and Ocean Sciences, No. 38.

This paper constitutes an expanded abstract of my Ph.D. Dissertation (see below, 1982).


Mills, C.E. and R.G. Vogt, 1984. Evidence that ion regulation in hydromedusae and ctenophores does not facilitate vertical migration. Biological Bulletin, 166: 216-227.

Medusae and ctenophores, like many types of gelatinous zooplankton, actively exclude sulphate ion from their mesogloeal body fluid and thus gain lift (buoyancy). It is hypothesized that vertically migrating species might show day/night variations in the rate of sulphate elimination to regulate buoyancy dynamically and that such changes are a major factor in vertical migration. To test this hypothesis, a series of laboratory experiments were conducted using medusae and ctenophores. Concentrations of radioactive sulphate were measured in equilibrium (uptake) experiments and concentrations of sodium, magnesium, potassium, and calcium ions were measured using atomic absorption spectrophotometry. No evidence of day/night (light/dark) changes in ion concentrations were found for the hydromedusae Aequorea victoria, Aglantha digitale, Gonionemus vertens, Mitrocoma cellularia, Phialidium gregarium, Polyorchis penicillatus, Sarsia tubulosa, and Stomotoca atra or for the ctenophore Pleurobrachia bachei. It is concluded that changes in ionic regulation are not a major factor in diel vertical migration. It is thus hypothesized that for these animals vertical migration is accomplished solely by swimming. **PDF file**


Mills, C.E. 1984. Density is altered in hydromedusae and ctenophores in response to changes in salinity. Biological Bulletin, 166: 206-215.

Laboratory experiments have determined the behavioral and gross physiological responses of hydromedusae and ctenophores subjected to sudden changes of salinities in the range that might be encountered in nature. Nine species of hydromedusae (Aequorea victoria, Aglantha digitale, Bougainvillia principis, Gonionemus vertens, Phialidium gregarium, Polyorchis penicillatus, Proboscidactyla flavicirrata, Sarsia tubulosa, Stomotoca atra) and two species of ctenophores (Bolinopsis infundibulum, Pleurobrachia bachei) were transferred from natural sea water of 30.5 o/oo to modified sea waters of 19-38 o/oo. Most species altered their density within a few hours by osmoconforming to salinities ranging from 23-38 o/oo, so that equilibrium buoyancy (either positive, neutral, or negative, according to species) was regained along with normal behavior. Even salinity differences of only 1-2 o/oo required 30-60 minutes adjustment time. Prior to regaining their equilibrium buoyancies, differences in relative density caused medusae and ctenophores to sink when introduced to low salinity water and to float in high salinity water. Hence, simple density differences combined with the natural intermittent swimming behavior of hydromedusae suggest that in many cases medusae may not actually be able to cross sudden density gradients. In the event that a medusa or ctenophore is moved into water of a different salinity, however, its ability to adjust will allow the animal to resume normal swimming and feeding activities within a short time. **PDF file**


Mills, C.E. and R.L. Miller, 1984. Ingestion of a medusa (Aegina citrea) by the nematocyst-containing ctenophore (Haeckelia rubra, formerly Euchlora rubra): phylogenetic implications. Marine Biology, 78: 215-221.

The rare ctenophore Haeckelia rubra (formerly Euchlora rubra) has long been known to have nematocysts rather than colloblasts in its tentacles. Five specimens were collected in the San Juan Archipelago, Washington State, USA in 1980 and 1981, and their feeding behavior was observed in the laboratory. We found that H. rubra readily eats the tentacles of a medusa, Aegina citrea, whose nematocysts (apotrichous isorhizas) are nearly identical in morphology to the nematocysts of the ctenophore. When H. rubra was offered 16 other species of hydromedusae and 1 siphonophore in the laboratory, the ctenophores showed little or no tendency to ingest these potential prey items. In addition to its routinely positive response to A. citrea, the ctenophore could be induced by manipulation and starvation to accept and ingest bits of the bodies of 4 additional species of hydromedusae and 1 siphonophore. These results, combined with the histological and rearing experiments of other investigators, leave little doubt that the nematocysts in H. rubra are not endogenous, but are "kleptocnidae" similar to those nematocysts retained and subsequently used by some species of nudibranchs that feed on Cnidaria. A close phylogenetic link between the Cnidaria and the Ctenophora is most unlikely. **PDF file**


Mills, C.E. 1983. Vertical migration and diel activity patterns of hydromedusae: studies in a large tank. Journal of Plankton Research, 5: 619-635.

Vertical distributions and swimming behaviors of 7 species of hydromedusae (Aequorea victoria, Bougainvillia principis, Gonionemus vertens, Mitrocoma cellularia, Phialidium gregarium, Polyorchis penicillatus, and Stomotoca atra) were observed over 24-h periods in a 2 m high, 1500 l transparent tank. In this tank, most species performed well-marked diel vertical migrations that were mediated by swimming. Manipulation of the light regime showed the diel swimming behaviors to be light-dependent rather than intrinsic, even in species that do not possess recognized photoreceptors. Correlations between vertical migration and spawning times for several species of medusae suggest that in cases when vertical migration reduces the distances between individuals (e.g., in mass movements to the surface) just prior to spawning, enhanced fertilization success may result from such movements. **PDF file**


Mackie, G.O. and C.E. Mills, 1983. Use of the Pisces IV submersible for zooplankton studies in coastal waters of British Columbia. Canadian Journal of Fisheries and Aquatic Sciences, 40: 763-776.

This study evaluates the usefulness of a small submersible for observations of the plankton. A method for calculating plankton densities from estimates of mean interanimal distances is described. Estimates made by this method were compared with estimates based on net sampling and were found to be in fair general agreement with them. Fragile gelatinous forms were better counted from the submersible, small organisms by netting. Some delicate species, known to be abundant from submersible observations, were never recognized in net samples. Submersible observations also gave important insights into vertical distribution of the plankton. Several species were found to exist within unexpectedly narrow and sharply defined layers, often at densities greatly surpassing density estimates based on net samples. In Saanich Inlet, B.C., plankton distribution was studied in relation to the seasonal formation and dispersion of the oxygen-deficient basin water. Other data deal with behavior, color change, bioluminescence, and vertical migration of planktonic organisms. We conclude that submersible observations are potentially valuable in plankton research, and we make recommendations regarding instrumentation and observer training as an aid in planning future dives. **PDF file**


Mills, Claudia E. 1982. Patterns and mechanisms of vertical distribution of medusae and ctenophores. Ph.D. Dissertation, Department of Biology, University of Victoria, B.C. Canada, 384 pp.

A series of 600 closing net plankton tows has been combined with extensive surface observations and 26 submersible dives to describe in detail the numbers and locations of medusae, siphonophores and ctenophores in Saanich Inlet, British Columbia and Friday Harbor, Washington. Included in this study are approximately 50 species of hydromedusae, 5 species of siphonophores, 4 species of scyphomedusae and 11 species of ctenophores; taxonomic keys are provided for the identification of these animals. Day/night plankton tows have revealed vertical migrations ranging from less than 25 m to 100 m for various local species of medusae.

Vertical migration of several species of hydromedusae has been generated in a 1500 l aquarium and monitored visually and electronically. Manipulation of the light regime showed diel swimming behaviours to be light dependent rather than intrinsic, even in species that do not possess recognized photoreceptors. The role of swimming and feeding behaviours of hydromedusae in vertical location and utilization of space is analyzed and documented with photographs.

Ionic and osmotic regulation of buoyancy with respect to vertical migration have been investigated in the laboratory. The hypothesis that vertical migration is facilitated by diel variation in active ionic transport has been ruled out by experiments using radioactive sulphate and atomic absorption spectrophotometry of various cations. It is concluded that vertical migration of medusae and ctenophores is accomplished by swimming. The ability of medusae and ctenophores to swim through salinity gradients and subsequently adjust to the change by osmoconforming has been investigated.

Unlike the distribution of marine benthic invertebrates which are primarily influenced by biological interactions between species such as predation and competition, distribution of medusae, siphonophores and ctenophores in the sea can be explained largely on the basis of the physical characteristics of individual organisms and their environment. The most important of these factors appear to be (1) the natural buoyancy of each species, which is influenced by intracellular sulphate regulation and the amount and distribution of proteinaceous tissue in the whole animal, (2) bell morphology and swimming pattern, (3) the density and oxygen profiles of the water column, and (4) the intrinsic capacity for diel vertical migration of the organism.


Mills, C.E. 1981. Diversity of swimming behaviors in hydromedusae as related to feeding and utilization of space. Marine Biology, 64: 185-189.

Feeding behaviors of the following 4 species of hydromedusae are described from field and laboratory observations: Proboscidactyla flavicirrata, Stomotoca atra, Phialidium gregarium, and Polyorchis penicillatus. Feeding efficiency of medusae has previously been considered equivalent to fishing with a given amount (combined tentacle length) of adhesive "fishing line;" however, detailed observation shows that behavior of medusae greatly modifies the fishing capacity of each species. It is hypothesized that in addition to (1) tentacle number and length, the following factors strongly influence feeding efficiency: (2) tentacle posture, (3) velocity of tentacles moving through water, (4) swimming pattern of medusa, (5) streamlining effects of medusa bell on water flow, (6) diameter of prey, (7) swimming pattern and velocity of prey. Each species of hydromedusa utilized the above factors in different combinations. **PDF file**


Mills, C.E. 1981. Seasonal occurrence of planktonic medusae and ctenophores in the San Juan Archipelago (NE Pacific). Journal of Biology, 39: 6-29.

Medusae, siphonophores, and ctenophores have been recorded year-round between 1976 and 1980 in surface waters near Friday Harbor, Washington. A detailed schedule of annual occurrence has been compiled for 41 species of hydromedusae, 5 species of siphonophores, 4 species of scyphomedusae, and 11 species of ctenophores. An annotated species list provides additional information on sizes of medusae, periods of sexual maturity, special locations, and polyp stages. The Strait of Georgia-San Juan Archipelago-Puget Sound region has an unusually high diversity and abundance of medusae and ctenophores. Diversity reaches a maximum in late spring, thereafter a smaller number of species maintains a high biomass of medusae throughout the summer. From late autumn through early spring few medusae are present. **PDF file**


Mills, C. and J.T. Rees, 1979. Bythotiara stilbosa, new species (Anthomedusae: Calycopsidae), from neritic waters in central California. Journal of Natural History, 13: 285-293.

Bythotiara stilbosa, a new species of hydrozoan in the family Calycopsidae, is described. Newly released medusae were collected from Bodega Harbor, a shallow embayment in central California, and raised to sexual maturity in the laboratory. Planulae were obtained from adults, but none were seen to settle. Adult medusae of B. stilbosa are separable from other species of Bythotiara by having irregularly spaced transverse folds of the gonad and possessing four tentacles. The bell is wider than it is high. Calycopsid medusae are usually considered to be oceanic in habitat, but the newly released medusae of B. stilbosa collected in Bodega Harbor indicate that the polyp occurs there as well. Thus, B. stilbosa can be considered a neritic, rather than oceanic species. The cnidom of B. stilbosa, consisting of microbasic euryteles, macrobasic euryteles, and microbasic mastigophores, is unique, as far as is known, for the entire family.


Mills, C.E. 1976. The association of hydractiniid hydroids and hermit crabs, with new observations from north Florida. pp. 467-476 In Coelenterate Ecology and Behavior (G.O. Mackie, ed.). Plenum Press, N.Y.

Although many studies have been undertaken to investigate various aspects of the symbiosis between hydractiniid hydroids and hermit crabs, a holistic understanding of the association fails to emerge. The association is not obligatory; many hermit crabs occupy clean shells, and the hydroids will settle on other hard substrates when these are available. By living on hermit crab shells, however, the otherwise planktivorous hydroids may adopt a benthic mode of feeding. The hydroids also avoid being silted over as long as their substrate-shell remains in the hermit crab shell pool. Some species of hermit crabs apparently prefer hydroid-covered shells to clean ones, but other species of crabs will not enter hydroid-covered shells. In some areas, the presence of hydroids may partition the shell resource, although the advantages of possessing hydroid-covered shells are not entirely clear. The effects of epizooic hydroids for hermit crabs in intra- and interspecific competition and in avoiding predation are not well understood. Data for the hydroids Podocoryne selena and Hydractinia echinata living on a variety of dead or live gastropod shell substrates in north Florida is included.


Mills, C.E. 1976. Podocoryne selena, a new species of hydroid from the Gulf of Mexico, and a comparison with Hydractinia echinata . Biological Bulletin, 151: 214-224.

A new species of hydroid, Podocoryne selena, is described from the north Florida Gulf of Mexico. This hydroid has mistakenly been called P. carnea in the past; polyps are very similar in the two species, but the medusae can be distinguished. P. selena medusae reach a maximum bell size of 1.5 mm with 8-14 tentacles and attain sexual maturity in 2 days; P. carnea reaches bell size of 2.0 mm with 8 tentacles and becomes sexually mature in 3 weeks.. Observations on the behavior of the polyps and medusae of P. selena are given. The hydroid species P. selena and Hydractinia echinata are both found living on hermit crab gastropod shells in the Gulf of Mexico. The two species are compared and morphological differences are illustrated with scanning electron micrographs. **PDF file**


Rees, J.T., C. Hand and C. Mills, 1976. The life cycle of Hydrocoryne bodegensis, new species, (Coelenterata, Hydrozoa) from California, and a comparison with Hydrocoryne miurensis from Japan. Wasmann Journal of Biology, 34: 108-118.

The life cycle of Hydrocoryne bodegensis new species is described and compared with its congener H. miurensis from Japan. Small colonies of 2-20 unbranched polyps of H. bodegensis were collected by SCUBA diving at 5-10 feet deep on rocks of a jetty at the entrance to Bodega Harbor, central California. Each polyp is up to 6 cm tall and has 30-50 capitate tentacles clustered on the hydranth and numerous medusa buds on branched pedicels near the base of the stem. Medusae were raised in the laboratory to sexual maturity at 3 weeks and were also collected from the plankton. Mature medusae are less than 3 mm tall and have 4 tentacles with prominent nematocysts clusters along their lengths and a large orangish manubrium with 4 interradial gonads, suspended on a prominent gastric peduncle.


Mills, C., J.T. Rees and C. Hand, 1976. A new species of Aglauropsis (Hydrozoa: Limnomedusae) from the northeastern Pacific, with notes on Aglauropsis conantii and Eperetmus typus. Wasmann Journal of Biology, 34: 23-42.

Aglauropsis aeora, a new species of limnomedusa in the family Olindiasidae, is described from the plankton off central California. Mature medusae may reach 20 mm in diameter and 15 mm in bell height, with thick, solid jelly. The manubrium hangs down about 1/2 the subumbrellar cavity and has 4 crenulated lips. There are about 200 tentacles, each ringed with nematocysts. This species does not have centripetal canals, but otherwise is rather similar to Eperetmus typus. It is also compared with an undescribed medusa from Japan that has previously been called E. typus. Planulae of A. aeora were obtained and settled and the primary polyp is described. The field biology of the hydroid is not known.



Mills, C.E., 2001. Ongoing invasion of the Asian purple varnish clam, Nuttallia obscurata, into Puget Sound waters: does anyone care? In The Puget Sound / Georgia Basin Ecosystem: Status, stressors and the road to recovery (Puget Sound Water Quality Action Team, editors and publisher) Conference Proceedings, Puget Sound Research 2001. Distributed on CD.

Nuttallia obscurata is believed to have arrived in the Strait of Georgia region in ballast water in the late 1980s and was first collected in 1991, just north of the Canadian border. It spread very rapidly throughout the southern Strait of Georgia, but is moving more slowly south into Puget Sound. I have been studying this clam since late 1997, primarily in San Juan County, Washington, where it has become common in the upper mid intertidal - localized densities can exceed 500/m2. It occurs in sediments ranging from cobbles to muddy sand, above (in tidal height) or near the native littleneck (Protothaca) and earlier-introduced Manila (Venerupis) and softshell (Mya) clams. N. obscurata is native to Japan, Korea, and perhaps China - its distribution is somewhat unclear because of historic taxonomic confusion among closely related species in Asia. It is not valued as a commercial species and apparently does not appear in markets in Japan, although it is eaten locally there. A map of its known occurrence throughout Puget Sound will be presented; most sites are north of Edmonds. It is also present on the outer coast in a few locations from Barkley Sound, Vancouver Island, to central Oregon.


Secord, D., J.S. Pearse, V.B. Pearse, and C.E. Mills, 1999. Regulation of binary fission in the sea anemone Anthopleura elegantissima: the role of clonal genotype and feeding regime. American Zoologist 39(5): p. 9A.

The intertidal sea anemone Anthopleura elegantissima of northeast Pacific rocky coasts facultatively undergoes binary fission. Published studies suggest that both genetic and environmental factors may underlie regulation of polyp fission, and hence the formation of large clonal aggregations, in this species. In a factorial laboratory experiment designed to minimize aggressive interactions between individuals, we independently varied clonal genotype (six clones from two locations in Washington State) and feeding regime (fed versus starved) to determine their effects on fission rate. We found that genotypes vary in their division frequency, that well-fed polyps are significantly more likely to divide than starved polyps, and that starved polyps move significantly more than fed polyps. Together with published data on agonistic interactions, patterns of genetic diversity, and the frequency of sexual recruitment, this study contributes to a mechanistic understanding of the origins and maintenance of clonal aggregations in these sea anemones.


Brodeur, R.D., J.E.Overland, G.E. Walters and C.E.Mills, 1998. Evidence for a substantial increase in biomass of gelatinous zooplankton in the Bering Sea: possible links to climate change. Oceanography, 11(2): 63-64.

We examined quantitative catches of large medusae from summer bottom trawl surveys which used the same methodology and sampled virtually the same station grid (n=346) on the eastern Bering Sea shelf from 1979 to 1997. This series shows a slight increase in biomass of medusae from 1979 to 1989, followed by a dramatic increase in the 1990s. The median biomass per station increased ten-fold between the 1982-89 and 1990-97 periods. The majority of this biomass was found within the Middle Shelf Domain, with a higher rate of increase in the Northwest shelf region. Whether this dramatic increase in biomass of gelatinous zooplankton has resulted from some anthropomorphic perturbation of the Bering Sea environment or is a manifestation of natural ecosystem variability is unclear. However, several large-scale winter/spring atmospheric (pressure indices, storm tracks) and oceanographic variables (temperature, water column stability) in the Bering Sea exhibited concomitant changes beginning around 1990, possibly indicating that a regime change occurred at this time.
See full article (above) published in Fisheries Oceanography, Dec. 1999.


Napp, J.M., C.T. Baier, R.D. Brodeur, J.J. Cullen, R.F. Davis, M.B. Decker, J.J. Goering, C.E. Mills, J.D. Schumacher, S. Smith, P.J. Stabeno, T.C. Vance and T.E. Whitledge. 1998. The 1997 Eastern Bering Sea shelf-wide coccolithophorid bloom: ecosystem observations and hypotheses. Eos, Transactions of the American Geophysical Union, Supplement 79(1), p. OS127.

Sometime between the spring diatom bloom (late April 1997) and the onset of fall storms (September 1997), an environmental "switch" or series of switches were set that favored the outbreak of a coccolithophorid population in the eastern Bering Sea. The bloom was first observed by water color in early July. In September the areal extent was documented with the first available SeaWIFS ocean color satellite images. During late September the bloom was ca. 700 x 300 km, and extended south from the Alaska Peninsula north to Nunivak Island and east from Bristol Bay to just west of the Pribilof Islands. To the best of our knowledge, this is the largest coccolithophorid bloom reported for the Bering Sea. Three U.S. sponsored programs (NOAA-COP, NSF-Inner Fronts, NOAA-NURP) made repeated observations on the biology and physics of the shelf ecosystem, February through September. Using these recently collected data, we: 1) describe properties of the bloom (e.g. the vertical extent of opaque water was 10­50 m with secchi depths as low as 2 m), 2) present relevant ecosystem observations (from nutrients to seabirds), and 3) analyze a climatology of environmental conditions to explore the hypothesis that anomalous conditions in the physical environment (winds, insolation, and water temperature) created conditions favorable for the coccolithophorid bloom.

Pearse, J.S., V.B. Pearse, D.L. Secord and C.E. Mills, 1994. Does feeding or starvation promote fission in the sea anemone Anthopleura elegantissima? American Zoologist 34(5): 126A.

In a 15-month laboratory experiment at Santa Cruz, California, we tested whether feeding, starvation, or change in feeding regime promotes fission in a clonal sea anemone. The 72 ramets from 11 clones, collected locally and at Friday Harbor and Tatoosh Island, Washington, fissioned mostly in late spring-summer, with little difference among collecting sites, but much variation within and among clones. Fission occurred mainly in ramets that were fed, either continuously or after 7 months of starvation. Little fission occurred with starvation, even in large ramets fed for 7 months before being starved. These experiments indicate that fission is not promoted by starvation as proposed previously; rather, it requires food -- as might be expected for an essential process in modular growth.


Mills, C.E. 1988. Species differences in diet and prey selection by hydromedusae. American Zoologist 28(4): 192A.

It is sometimes assumed that jellyfish are indiscriminate predators on available zooplankton and that copepods provide the mainstay of most jellyfish diets. Gut analyses performed on individually field-caught medusae show that different medusae occupying the same water mass have very different diets and that these diets are species-specific. For example, in May 1987 in Friday Harbor, Phialidium ate 80% eggs and embryos, Mitrocomella ate 70% larvaceans, Bougainvillia ate 90% barnacle nauplii, Aequorea ate 90% hydromedusae, and Sarsia ate 40% copepods and 40% barnacle nauplii. Diets for all species change with seasonal availability of prey.

As a result of whole animal as well as microscopic studies, I propose that prey selection by hydromedusae is determined by a combination of stereotyped behavior and anatomy. Species-specific nematocyst arrays on the jellyfish tentacles and manubrium are a general indicator of diet, but the correlation is not perfect. Prey selection is also dependent on the species-specific swimming patterns that result from the interaction of distinct bell morphologies (affected by passive flow interactions) and different pulsation rhythms (driven by endogenous pacemakers). Time allocations between swimming and feeding activities also vary by species.


Mills, C.E. 1984. A functional analysis of the medusan body plan: morphological versus reproductive adaptations to various habitats. American Zoologist, 24(4): 105A.

The medusan body plan appears to have changed little since the Precambrian in its basic form, consisting of a more or less hemispherical bell with marginal tentacles. Each of the 800 present-day species of hydromedusae represents some minor morphological variation on this simple body plan. The behavior and ecological role in the plankton of each species seems to be determined by small changes in bell and tentacle form, oveall buoyancy, and pulsation rate (which is driven by the neural pacemaker), and whether swimming and feeding activities are coupled or separated in time. While comparing morphological and functional parameters between coastal and open-ocean species of hydromedusae, it was found that no special set of morphological characters typifies either habitat. On the other hand, there are many peculiar sexual and asexual reproductive traits that appear more frequently in open ocean animals. It is concluded that reproductive characteristics may be more plastic than morphological characteristics for hydromedusae during adaptation to different habitats.


Mills, C. 1982. In situ quantitative plankton observations using a submersible (Pisces IV). Eos, 63(45): 956.

Over 40 submersible dives have been made in Saanich Inlet, B.C. during 7 separate weeks from 1980 to 1982 in an ongoing program of observation of zooplankton (day and night) throughout the 200 m water column. Precise information on depth distribution and corresponding numerical abundance has been obtained for prominent zooplankton species. Saanich Inlet is biologically very stratified, with most planktonic species occurring within rather narrow depth limits above a low-oxygen or anoxic bottom layer. Most individuals of a species occurred in bands 5-20 m thick. Typical maximum abundances seen (these not all on the same dive) include: 50,000 Euphausia pacifica /m3, 100 Cyphocaris challengeri /m3, 500 Sagitta elegans /m3, 10,000 Neocalanus plumchrus /m3, 500 juvenile Munida quadrispina /m3, 25 Aglantha digitale /m3, 20 Bolinopsis indundibulum /m3, and 10,000 Oikopleura dioica /m3. Smaller copepods can also be identified and counted with modifications of the standard lighting and at some sacrifice of distant (and more comprehensive) vision. Estimates of between-animal distances, converted to number per unit volume, seems to be the most usable system for estimating in situ abundances.


Mills, C.E. 1980. Regulation of buoyancy in hydromedusae. American Zoologist, 20: 820.

Lab experiments determined the responses of hydrozoan medusae to sudden changes of salinity in the range that might be encountered in nature. Eight species of Puget Sound medusae were transferred from natural seawater of 30 psu salinity to modified seawater of 21-38 psu. Each species adjusted its density in less than 6 hours so that its natural buoyancy (either positive, neutral, or negative) was regained along with normal behavior. Differences in salinity of 1-2 psu required at least 10 minutes adjustment time, during which medusae would sink below less saline water or rise above more saline water whenever they stopped swimming. Hence, simple density differences combined with the natural intermittent swimming behavior of hydromedusae suggest that in most cases medusae will not actually cross sudden density gradients. In the event that a medusa is moved into water of a different salinity, its ability to adjust will allow the medusa to reassume normal activities within a short time. Osmotic and active ion pumping medhanisms of buoyancy regulation have been investigated.
See pair of full articles (above) published in Biological Bulletin, 1984.

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