Moles and shrews can smell underwater

Moles and shrews can smell underwater

Moles and shrews can smell underwater
mongabay.com
December 20, 2006

Mammals can smell underwater according to a study published in the December 21 issue of the journal Nature.

The water shrew can detect odors underwater. Photo by Kenneth Catania

Kenneth Catania, an assistant professor of biology at Vanderbilt University and recipient of a $500,000 “genius grant” this year from the John D. and Catherine T. MacArthur Foundation, found that moles and shrews are capable of detecting prey underwater using their sense of smell.

“This came as a total surprise because the common wisdom is that mammals can’t smell underwater,’ said Catania. “When mammals adapt to living in water, their sense of smell usually degenerates. The primary example is the cetaceans — whales and dolphins — many of which have lost their sense of smell.”

Catania used a high-speed camera to show how the animals smell underwater. A news release from Vanderbilt explains Catania experiment:

Catania mounted a high-speed video camera so that it pointed up through the bottom of a glass tank. Then he stuck various objects on the bottom of the tank — pieces of earthworm, small fish, insect cuticle and blobs of wax and silicon — and observed the moles’ behavior. He saw that, when the moles approached one of these targets, they would blow bubbles that came into contact with the target’s surface and then were sucked back into the nostrils.

The star-nosed mole in mid-sniff underwater. Photo by Kenneth Catania

“Because the olfactory nerves in the nose are covered with mucous, odorant molecules are all water soluble,” Catania said. “So, when these bubbles come into contact with an object, it is almost inevitable that odorant molecules will mix with the air and be drawn into the nose when the bubble is inhaled.”



“Now, the question is, ‘What other semi-aquatic mammals do this?'” Catania said. “Do animals like otters and seals do anything similar? Or is there a size limit and it only works for smaller mammals?”

This article is based on a news release from Vanderbilt University.