Blind Cavefish Also Hard of Hearing

Joseph Castro, LiveScience Contributor

Date: 27 March 2013 Time: 03:21 PM ET

After generations of living underground and in perpetual darkness, species typically lose their eyesight. Scientists have observed this phenomenon in a range of creatures, including moles, shrimp, flatworms and fish. But new research shows that compared with their surface-dwelling relatives, at least two species of amblyopsid cavefish are partially deaf, in addition to being blind.

"The first hypothesis we had was that these fish that lost their sight should have an increase in hearing capabilities," said lead researcher Daphne Soares, a sensory neuroscientist at the University of Maryland. "It was a big surprise when we found they were a little deaf, and it took a while to come up with an understanding of what was happening."

In humans, the loss of sight is sometimes accompanied by better hearing, at least in people who became blind early in life. But until now, research looking at blind fish species hasn't shown the same phenomenon. For example, the cave and surface forms of theMexican tetra (Astyanax mexicanus) hear equally well; same thing goes for the molly Poecilia mexicana.

Continued:  http://www.livescience.com/28235-cavefish-hearing-loss.html