In the seas of the world where sharks of all kinds are fast disappearing, a deep-diving San Francisco biologist and his colleagues have discovered a new species of shark among the Galapagos Islands.
With its razor-sharp teeth, the shark is well equipped for its role at the top of the ocean's food web, said John McCosker, the chief of aquatic biology at the California Academy of Sciences who led the discovery. But it's not much like the feared great white: This one is a modest-size bottom-feeder.
McCosker, together with Carole C. Baldwin, curator of fishes at the National Museum of Natural History in Washington, and Douglas J. Long, a shark specialist at the Oakland Museum, reported on the new species in the latest issue of Zootaxa, an international journal published in New Zealand.
Life on the bottom
The shark is a member of the catshark tribe, a bottom-dwelling sluggish group of fishes with small teeth that are found all over the world, McCosker said. The team has named the new species Bythaelurus giddingsi.
"The closest living relative of this species would be the swellshark, a shallow-water coastal species seen by scuba divers in California," McCosker said. "They spend their life on the bottom and probably feed on other fishes and invertebrates.
"Their teeth are small and sharp and evolved to grasp their prey before engulfing it."
McCosker and Baldwin collected seven small to moderate-size samples of the new shark while diving inside the submersible called the Johnson Sea-Link during an expedition to the Galapagos Islands in 1998 - a long time ago, it may seem.
7 sharks captured
But in the slow-moving ways of animal identification and naming - a science known as taxonomy - the team's detailed description of the new shark species has just been reported.
The seven sharks ranged in length from 9 to 18 inches, and were all sexually immature. As McCosker and Baldwin syphoned them aboard the submersible, several sharks swam past appearing much larger and more mature, "either too fast or too large to be collected," McCosker said.
To determine that the sharks were in fact members of a new species, the scientists carefully measured them, dissected them, analyzed them and described each organ. All seven are now preserved for other scientists at the academy in Golden Gate Park.
Roughly 375 species of sharks exist in the world's oceans, and a new one may not seem all that important, but every shark species around the world is being heavily overfished - primarily to harvest their fins for shark fin soup, a major Asian delicacy. The result, McCosker noted, is a worldwide decline in shark populations.
"Sharks are the top predators of the ocean, and if any one of them goes extinct it can cause the loss of an entire ocean food web, which is why I want to save those primary predators," McCosker said.
Named after a hero
The scientists named the new species for Al Giddings, a retired San Francisco underwater filmmaker who was with McCosker and Baldwin in the Galapagos directing an Imax film for the Smithsonian Institution at the time of the discovery.
Giddings, 74 and a veteran diver now living in Montana, rescued a companion who was badly bitten by a great white shark off the Farallones 40 years ago by diving into the blood-covered water, pulling the injured victim away from the beast's teeth, and towing him to the fishing boat where companions lifted him aboard. The companion survived.
David Perlman is The San Francisco Chronicle science editor.