Stereo Sensors Guide Fish Through Water

December 31, 2006

Release from: Tina Hesman Saey
St. Louis Post-Dispatch

ST. LOUIS - Two years ago, Paul A. Cziko and his diving partner dove under more than 20 feet of sea ice in the frigid waters off the coast of Antarctica.

They were looking for the eggs of the naked dragonfish. Instead, Cziko, a researcher at the University of Illinois Urbana-Champaign, discovered a previously unknown species of fish.

A female fish sitting on a large, flat rock caught Cziko's eye. He knew this fish was different. So the divers threw a mesh bag over the fish and brought her ashore for further study.

Cziko, now at the University of Oregon, made careful measurements of the new fish and compared it with other fish in the area. It soon became apparent that the lone female was the first member of her species found by humans. The fish resembles one caught in 1975 off the Antarctic Peninsula, called Cryothenia peninsulae, but has a special sensor that sets it apart.

Cziko could have named the fish after himself, another scientist or a rock band, but he is a purist. He wanted a name that tells something about the fish. With the help of a classics professor, he chose the Greek name Cryothenia amphitreta. Cryothenia means "from the cold," and amphitreta means "a cave with two openings."

The second half of the name refers to a structure on the fish's forehead called the interorbital pit. The pit is an opening to a series of canals under the scales that help fish sense changes in water pressure, such as those produced when another fish swims by.

The newly discovered fish has a pit with two openings, whereas its cousin has only a single opening. The double pits make more sense to Cziko. Like stereo vision or sound, dual pressure sensors might help the fish locate prey better than a mono version can.