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On the Ocean Floor, Extreme Worms Eat Whale Bones

By Kate Ruder


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Extremophiles
Oceans
Worms

A female worm dissected from the whale bone, showing green “root” tissue and white ovaries.
In the Pacific Ocean, scientists have found two new and peculiar species of deep-sea worms. The worms—only a few centimeters long—live and feed on whale bones left behind from whale carcasses that have sunk to the ocean floor.

“We had no idea what they were, but they were covering the whale bones and they had such a strange appearance,” says Shana Goffredi of Monterey Bay Aquarium Research Institute (MBARI) in Moss Landing, California.

Using DNA analysis, Goffredi and her colleagues discovered that the organisms are actually two previously unknown species of worms that they later named Osedax, which means “bone-devouring” in Latin. They are related to worms that live near thermal vents in the ocean.

The worms are remarkable in their appearance and diet. Called tubeworms, the soft worms live inside protective sheathes; they have feathery, red plumes that stick out and cover the whale bones in a ruby carpet.

Their upper body is like a worm, but their lower body flares out into green, root-like tissue that burrows into the whale bone. No other worm is known to have this type of tissue.

With no mouth or gut, the worms rely on bacteria that live on their “roots” to extract nutrients from the whale bone. The symbiotic bacteria, called Oceanospiralles, degrade oil from the bones.

Arm of the remotely operated vehicle picks up a whale rib that is covered with worms.
The same bacteria could also be useful to humans. They survive extremely cold temperatures and high pressure, and scientists are studying their potential to clean up oil spills and to develop cold-water detergents.

“If you go to weird places, you just find things that people haven’t seen before,” says Robert Vrijenhoek of MBARI, who led the study that appears online today in Science.

The discovery was purely accidental, according to Vrijenhoek. He and his colleagues were exploring an ocean canyon at the bottom of Monterey Bay when they stumbled upon the worms.

A female tube worm lives inside a tube that may be filled with as many as 100 microscopic males. The number of males in individual tubes directly correlates with the size of the females, the scientists report. Bigger females have more males.

When a whale dies it sinks to the bottom of the ocean and is then known as “whale fall.” It becomes a source of food for fish, crabs, octopuses, worms and microscopic organisms.

“Whale fall habitats support communities of organisms for a very long time,” says Craig Smith of the University of Hawaii at Manoa in Honolulu, who is an expert on whale falls. It can take up to 50 years for a large whale skeleton to decompose.

The new worms were found on a gray whale carcass nearly two miles (3,000 meters) below the surface of the ocean in Monterey Bay, which is a migration corridor for whales.

Rouse, G.W. et al. Osedax: Bone-eating marine worms with dwarf males. Science 305, 668-671.

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