By Hans-Dieter Sues
In the movie The Lost World (1997), the eccentric chaos theoretician Dr. Ian Malcolm (Jeff Goldblum) remarked on the all-too-soon apparent instability of the “Jurassic Park” world: “Life will find a way.” It always does.
Some animals and plants make a living in almost unimaginably weird ways. For an evolutionary biologist like me, discoveries of such new modes of life always are exciting news.
In 2002 scientists from the Monterey Bay Aquarium Research Institute (MBARI) made an amazing find off the coast of California at a depth of almost 2,900 meters (9539 feet)–worms that settle on whale carcasses that have sunk to the bottom of the ocean and subsist on their bones.
These worms lack eyes and mouths. One end of their bodies sports green, rootlike structures that extend into the bones. These “roots” harbor symbiotic bacteria that are capable of digesting proteins and perhaps fats within the whale bone and thereby provide nutrients for their worm hosts.
The worms are highly specialized bristle worms (polychaetes) that were classified in a new genus Osedax (“bone-eater”).
Watch this MBARI video about bone-eating worms in the wild:
Since the original discovery, researchers have found a considerable diversity of these bizarre creatures. Different species of bone-eating worm settle on cadavers of different species of whales.
Experiments with cow bones have shown that the worms are by no means limited to consuming whale bones. One species of worm does actually not live on whale carcasses but grows a long tube and sends tendrils into the mud near whale carcasses, perhaps to probe for buried pieces of bone.
A team of American and German researchers has now found evidence for the presence of bone-eating worms as early as 30 million years ago.
Bone-eating worms are soft-bodied and thus very unlikely to become fossilized. However, they generate characteristic boreholes in the bones.
CT-scanning of bones of fossil whales from Oligocene sedimentary rocks on the Pacific coast of the United States revealed holes that match those produced by present-day bone-eating worms in size and shape.
The whale fossils in question belong to extinct relatives of today’s baleen whales (mysticetes).
Unlike the nutrient-rich waters near the ocean’s surface, the vast, dark plains of the ocean floor are largely devoid of food. In this setting, anything–even animal bones–represents a potential source of nourishment.
From the new fossil finds, it appears that bone-eating worms evolved around the time whales started living in the open ocean and their carcasses provided a new food source for the denizens of the deep.
Hans-Dieter (Hans) Sues is a vertebrate paleontologist based at the National Museum of Natural History in Washington, D.C. He is interested in the evolutionary history and paleobiology of vertebrates, especially dinosaurs and their relatives, and the history of ecosystems through time.
A former member of the National Geographic Committee for Research and Exploration, Hans has traveled widely in his quest for fossils and loves to share his passion for ancient life through lectures, writings, and blogging.
More about bone-eating worms from National Geographic: