for National Geographic News
DNA evidence has helped identify 113 new sharks and rays—including a skinny saw shark, a swell shark that looks like it swallowed a Frisbee, and a river shark (see photos)—scientists announced Thursday.
Nearly half of the newly named sharks and other species are found only around Australia. The discoveries increase the continent's tally of known sharks and rays by a third. One of the new fish, the collared carpet shark, is so rare that the only known specimen was found in the belly of another shark.
Some of the new species are already threatened with extinction, scientists say, and many of the sharks and rays have yet to be named.
(Also see: "New Sharks, Rays Discovered in Indonesia Fish Markets" [March 31, 2007].)
Defined by DNA
During the 18-month study, researchers used genetic techniques to help scientifically describe, for the first time, species already in museum collections in Australia, New Zealand, and Europe.
"We reviewed the entire shark and ray fauna," said fish taxonomist Peter Last, who led the project for Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO).
At first glance, some of the fish appear very similar, making it tough to tell different species apart. Some even share the same habitat. "Quite often, they will swim together," Last said.
Existing descriptions—many of them brief and lacking detail—weren't much help, Last said.
But by analyzing the species' DNA, the scientists were able to uncover invisible distinctions.
"In some cases, what was thought to be a single species of shark turned out to be something like five species," he said.
Among these previously "hidden" species is the newly described maugean skate, already listed as endangered by the International Union for the Conservation of Nature.
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