A dozen species of worms that devour the skeletons of whales and two species of snails related to the gastropods that munched dinosaur bones have been discovered by Monterey Bay Aquarium Research Institute scientists.

The bizarre, previously unknown creatures apparently soften bones for hundreds of other deep-sea scavengers, including anemones and crabs, according to the landmark research conducted over the past six years off the coast of Monterey.

The discoveries, which include worms that sink roots into bones as if they were trees, show an ecological connection between some of the largest and smallest creatures in the sea and also broaden scientists' understanding of the ocean ecosystem.

"Even a dead whale has a valuable role in the marine ecosystem because different species feed on whales at different depths," said evolutionary biologist Robert Vrijenhoek, a senior researcher at the institute. "We think the bone-eating worms are critical. The worms come first, then snails and then crabs. Those bones are very rapidly degraded, which means that the material is recycling back into the system."

Deep research

The research, much of which was conducted 2 miles deep in Monterey Canyon, is outlined in 10 scientific papers, the latest of which was published by biologist Lonny Lundsten in collaboration with Vrijenhoek and six other researchers.

The findings build upon the discovery by Vrijenhoek in 2002 of thousands of reddish worms clinging to the carcass of a gray whale. Using video images from a remote-controlled submarine, Vrijenhoek determined that they were related to the giant tubeworms discovered in deep-sea volcanic vents.

Subsequent DNA analysis revealed that they were an entirely new genus of annelid worms, which researchers named Osedax, the Latin term for "bone devourer."

Three species of Osedax were initially identified. Inspired, researchers sank five whale carcasses at different depths in Monterey Canyon. Twelve additional species of Osedax have been discovered since 2006, and every one of them is like nothing anyone has ever seen before in nature, Vrijenhoek said.

Worms with roots

The worms, which grow to about 2 inches long, have no mouth, teeth or gut. Instead they colonize skeletons, sink roots into the bone and suck out nutrients.

"As far as we can tell, they dissolve the bone by producing an acid-based mucous," he said. "The worm's roots are packed with bacteria. We know that the worms derive some of their nutrition by digesting the bacteria."

This unusual discovery created much excitement in the laboratory, but the surprises were just beginning. At first, only female worms could be found, Vrijenhoek said. Then, under magnification, hundreds of microscopic male worms were found in a tube amid a slimy green substance attached to the female's body.

Evidently, he said, the throngs of tiny males are there solely to fertilize the tens of thousands of eggs that are produced by the female and kept in an ova sack.

"They are essentially larvae that produce sperm," Vrijenhoek said. "I don't know of any smaller males in the animal kingdom. There really isn't anything else on Earth to compare it with."

Dinosaurs to whales

During their studies, two new species of bone-eating sea snails from the genus Rubyspira were also discovered.

"They seem to be living relatives of snails that used to make a living eating the bones of the plesiosaurus, the long-necked marine reptiles, back in the cretaceous period, before the dinosaurs went extinct," Vrijenhoek said. "When the reptiles went extinct, they started eating whale bones."

The researchers found that different species of worms and snails feed at different depths. And these slimy bone-devouring creatures don't limit themselves to whale skeletons. Researchers sank seal, cow and pig bones, which were all colonized by worms.

"The worms don't care. They just eat bones," Vrijenhoek said. "They can pretty much live on any bone that they come upon."