A Real Fish Story: New Pool of Old Species Found
Newly discovered population of ancient fish may provide clues to history of evolution.
BOSTON — Tipped off by the contents of a fishmonger's cart, marine biologists have found a new population of a rare, ancient lineage of fish that until 1938, zoologists knew only as fossils.
Over the past 60 years, the only known population was centered around the Comoros Islands off Mozambique. Now, a new population has been found 6,200 miles to the east in the waters off the Indonesian island of Sulawesi that may fill in gaps in the history of life on earth.
Virtually unchanged over their 410-million-year history, coelacanth (pronounced SEE-luh-canth) have launched untold science-fair projects, school reports, and a heated debate among evolutionary biologists over the fish's possible role as forerunner to four-legged, land-based vertebrates. They were even the inspiration for the movie "The Creature From the Black Lagoon."
The new group provides fresh opportunities to study the creatures, researchers say, and to use DNA studies to fill a gap in their history that spans the past 65 million years. Researchers are eager to compare specimens from Indonesia with their Comoros counterparts to see if the discovery highlights a new species. The find also raises hopes that coelacanth can be brought back from the brink of extinction. "The thought of finding another population is mindboggling," says Christopher McGowan, a zoology professor at the University of Toronto and a senior curator at the Royal Ontario Museum.
The process of discovery began last September as marine biologist Mark Erdmann and his bride walked though a fish market on Sulawesi. His wife spotted the unmistakable form of a coelacanth in a fish cart. The couple were unable to buy the fish, but they did take photos. Since then, Dr. Erdmann has spent time interviewing fishermen and photographing their catches.
In July, fishermen landed a 4-foot, 64-pound coelacanth that survived long enough to be photographed swimming with Erdmann's wife and some of the local residents. Based on his research, Erdmann and his colleagues - Roy Caldwell of the University of California at Berkeley and M. Kasim Moosa of the Indonesian Institute of Science in Jakarta - concluded they had discovered a new population, not merely "strays" from the Comoros. Their discovery appears in today's edition of the journal Nature.
Ugly enough to chase Julia Child from the stock pot, coelacanth reach lengths of up to five feet and weigh as much as 200 pounds. They live among the caves and crevices along the flanks of volcanically active islands. At night, they forage for food down to depths as low as 500 meters. Foot-long coelacanth pups are born alive and fully formed.
Coelacanth and three classes of lungfish are the only surviving representatives of an enormous group that thrived during the Devonian period about 400 million years ago, says William Bemis, a biology professor at the University of Massachusetts at Amherst. These so-called lobe-finned fish are those from which land-based vertebrates are thought to have evolved. "Anything that contributes to our knowledge of lobe-finned fish is important" in piecing together that story, he says. Hence the scientific excitement.
Coelacanth also are in deep trouble; their numbers are falling as individuals get trapped in shark nets and die. In the Comoros Islands, a coelacanth population once thought to number about 500 has fallen to fewer than 200. In addition, Dr. Bemis says, black-market trade in coelacanth fluids is emerging in Asia, where they are used as a folk medicine.
Erdmann, a postdoctoral fellow at UC Berkeley, says that he has been working with the Indonesian government to focus more of its marine-conservation efforts on coelacanth and hopes the creature acts as "a keystone species to influence marine conservation" in the island nation.
"It would be a pity if the coelacanth were to go extinct," Bemis adds. "It would be like wiping out the last dinosaur."
In a larger sense, the discovery highlights how little humans know about the variety of marine life that lies beneath 75 percent of the planet's surface. "The process of discovering the kind of biological richness that exists is an ongoing one," Bemis says. "We need to try to get as much done as we can before it's too late."