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Neuroscience For Kids


Mammals that can SMELL underwater!
January 2, 2007

When you (and most other mammals) dive underwater, you can't smell anything because it is impossible to inhale without getting water in your lungs. A recent discovery by Dr. Kenneth C. Catania at Vanderbilt University shows that two mammals are capable of sniffing underwater.

Dr. Catania used high-speed video recordings to film the star-nosed mole (Condylura cristata) and water shrew (Sorex palustris). He noticed that these animals blew small air bubbles and then inhaled the bubbles when they hunted for food. To test his theory that the animals were using the bubbles to smell, he built an underwater trail using the starnose scent of earthworms, a favorite food of the mole, or the scent of fish, a favorite food of the shrew.

The moles and shrews Dr. Catania tested were able to follow the trails: the five moles had an accuracy ranging from 75% to 100% and the two shrews were accurate on 80% and 85% of the trials. While tracking, the animals "sniffed" in a way similar to when they were out of water. For example, they inhaled and exhaled 0.06-0.10 ml of air at a rate of 8-12 times per second.

Can other mammals, such as seals and otters, also smell underwater? Future experiments may reveal more ways that the nose is used.

Did you know?In 2006, Dr. Catania received a $500,000 "genius grant" from the John D. and Catherine T. MacArthur Foundation for his work on the star-nosed mole.

References and more information:

  1. Catania, K.C., Olfaction: Underwater 'sniffing' by semi-aquatic mammals, Nature, 444: 1024-1025, 2006.
  2. Vanderbilt University Press Release - great photos!
  3. MacArthur Foundation Fellows Program

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