BEIJING, Dec. 26 (Xinhuanet) -- Kenneth Catania, a biologist at Vanderbilt University, U.S., discovered that moles and shrews can smell underwater, which was considered impossible by scientists for a long time, according to the latest Nature.
Catania's first clues came in the 1980s, when he was a graduate student studying star-nosed moles, which hunt for prey underground and underwater. Catania noticed that when they were underwater, they sometimes released a stream of bubbles, at about two bubbles a second. If the moles were holding their breath, it did not make much sense for them to be leaking.
"It seemed unusual," Catania said. "I couldn't think of any good reason for an animal to do this."
Catania made his original observations with the naked eye, but in recent years has been recording star-nosed moles with high-speed video. He noticed that the star-nosed moles were actually producing up to a dozen bubbles each second, but most of the bubbles never detached from their noses. Instead, the animals sucked the bubbles back in.
The bubbles resembled the puffs of air the moles used to smell objects out of water, Catania noticed. To test that idea, he ran an experiment.
He laid down an underwater scent trail leading to little bits of food.
The moles could follow the trails with great accuracy which led him to believe that they were using the air bubbles to smell.
Catania wondered if any other mammals could sniff underwater. He tested water shrews, which are known to swim for their prey. In the scent trail test, he found, the water shrews did as well as the star-nosed moles.
Bubble-sniffing is a striking example of how evolution tinkers with bodies, rather than rebuilding them from scratch, he suggested.
(Agencies)
