Weird New Ghostshark Found; Male Has Sex Organ on Head

National Geographic 22 Sep 09;

September 22, 2009—California has a new star, the Eastern Pacific black ghostshark.

Photo from MBARI.

But the newly identified species prefers to stay out of the sun—and the spotlight. And with a club-like sex organ on its forehead, the male ghostshark isn't likely to get any leading man roles.

The new ghostshark uses winglike fins to "fly" through its dark habitat, thousands of feet deep off the coasts of California and Mexico's Baja California peninsula, a new study says.

The ghostshark seems to have flown under the scientific radar too. Since the 1960s experts have been finding specimens of the strange, 3-foot-long (0.9-meter-long) fish, which ended up nameless in museum collections around the world.

It wasn't until after a team recently searched through shelves of "dead pickled fish" that the Eastern Pacific black ghostshark was recognized as its own new species, said study co-author Douglas Long, chief curator in natural sciences at the Oakland Museum of California. The specimens' unique proportions, precisely measured, gave the fish away as a separate species of ghostshark.

Ghostsharks in Chimerical Company

The shark-like animal belongs to the mysterious and little-studied chimeras, perhaps the oldest group of fish alive today.

These "living fossils" branched off from sharks about 400 million years ago. They may have survived by adapting to extreme deep-sea environments, Long said.

The newfound ghostshark belongs to the "big black chimeras," a group whose species number has exploded in recent years, thanks to improved diagnostic techniques, according to the new study, published in the September issue of the journal Zootaxa.

Chimeras display some unusual features not seen in other living animals, Long said.

Male chimeras, for example, have retractable sexual appendages sprouting from their foreheads. These organs, which resemble a spiked club at the end of a stalk, may be used to stimulate a female or to pull her closer—though these are still assumptions, Long said.

Long said the odd fish shows how complex the deep ocean can be—as well as the vast potential for encountering weird new creatures.

"It's like Christmas. You don't what you're going to get," he said, "but you know it's going to be great."

—Christine Dell'Amore

New species of ghostshark from California and Baja California
Ancient and bizarre fish named by California Academy of Sciences researchers
California Academy of Sciences, EurekAlert 21 Sep 09;

New species are not just discovered in exotic locales—even places as urban as California still yield discoveries of new plants and animals.

Academy scientists recently named a new species of chimaera, an ancient and bizarre group of fishes distantly related to sharks, from the coast of Southern California and Baja California, Mexico. The new species, the Eastern Pacific black ghostshark (Hydrolagus melanophasma), was described in the September issue of the international journal Zootaxa by a research team including Academy Research Associates David Ebert and Douglas J. Long.

Additional co-authors included Kelsey James, a graduate student at Moss Landing Marine Laboratories, and Dominique Didier from Millersville University in Pennsylvania. This is the first new species of cartilaginous fish to be described from California waters since 1947.

Chimaeras, also called ratfish, rabbitfish, and ghostsharks, are perhaps the oldest and most enigmatic groups of fishes alive today. Their closest living relatives are sharks, but their evolutionary lineage branched off from sharks nearly 400 million years ago, and they have remained an isolated group ever since. Like sharks, chimaeras have skeletons composed of cartilage and the males have claspers for internal fertilization of females. Unlike sharks, male chimaeras also have retractable sexual appendages on the forehead and in front of the pelvic fins and a single pair of gills. Most species also have a mildly venomous spine in front of the dorsal fin. Chimaeras were once a very diverse and abundant group, as illustrated by their global presence in the fossil record. They survived through the age of dinosaurs mostly unchanged, but today these fishes are relatively scarce and are usually confined to deep ocean waters, where they have largely avoided the reach of explorers and remained poorly known to science.

This new species belongs to the genus Hydrolagus, Latin for 'water rabbit' because of its grinding tooth plates reminiscent of a rabbit's incisor teeth. This new species was originally collected as early as the mid 1960s, but went unnamed until this year because its taxonomic relationships were unclear. A large blackish-purple form, Hydrolagus melanophasma (melanophasma is Latin for 'black ghost'), is found in deep water from the coast of Southern California, along the western coast of Baja California, and into the Sea of Cortez (Gulf of California). This species is known from a total of nine preserved museum specimens, and from video footage taken of it alive by a deep-water submersible in the Sea of Cortez.

Renewed exploration of the world's deep oceans and more extensive taxonomic analysis of chimaera specimens in museum collections have led to a boom in the number of new chimaera species discovered worldwide in the last decade, including two species from the Galápagos Islands named by Didier, Ebert, and Long in 2006 that were originally collected by Academy scientist John McCosker. With further advances in research and discovery, perhaps more will be known about these living fossils and their diversity in the world's oceans.