Whale worm

Animal Facts

  • Scientific Name

    Osedax spp

  • Animal Type


  • Diet

    nutrients supplied by symbiotic* bacteria breaking down oil and fats in whale bone

  • Size

    1- 2.5 inches (2.5-6.3 cm) depending on the species

  • Relatives

    vent tube worms; Phylum: Annelida; Class: Polychaeta

Natural History

Scientists working at the Monterey Bay Aquarium Research Institute (MBARI) in 2004 discovered two new species of unique tubeworms that feed on the bones of dead whales. The worms are in a new genus called "Osedax," which is Latin for "bone devourer."

The worms' bodies and feeding strategies are very different from most animals. They have no eyes, legs, mouths or stomachs, but they do have colorful feathery plumes and green "roots." The reddish plumes extend into the water and act as gills. They connect to a muscular trunk, which can be withdrawn into a transparent tube when the worms are disturbed. At the other end of the trunk, hidden inside the whale bone, the body widens to form a large egg sac. The green roots, branching off from the egg sac, grow into the whale bone similar to the way garden plant roots spread into the ground. They are filled with symbiotic bacteria that break down the fats and oils inside the bone, providing food for the worms. 


Whale carcasses—or whale falls, as they are called—represent a massive input of food into the generally food-limited environment of the deep sea. One whale fall can provide as much organic material as thousands of years of marine snow, the organic debris that drifts down from surface waters to sustain life in the deep.

Commercial whaling which began in the 1800s may have driven some whale worm species to extinction. Many whale populations are estimated to be only ten to 25% of their historical levels despite the 1982 International Whaling Commission's moratorium on commercial whaling. Fewer whales means fewer whale falls and less habitat for whale-fall species such as whale worms.

Cool Facts

Whale skeletons support so much life because they contain an enormous amount of oil. Large whale bones can be more than 60 percent oil by weight, for example a 90 ton whale is estimated to have 5 tons of oil in its bones, a veritable feast for oil-eating bacteria. 

Scientists who discovered these tube worms were puzzled by the lack of male tube worms until a close-up examination of female worms revealed microscopic males living within their bodies. They looked as if they had never developed past their larval stage but they contained copious amounts of sperm. As many as 50-100 males may reside in one female. MBARI scientist Robert Vrijenhoek said "These worms appear to be the ecological equivalent of dandelions—a weedy species that grows rapidly, makes lots of eggs, and disperses far and wide." 

After a whale skeleton has been consumed, all the worms at that site will die off. Before this happens, they must release enough eggs or larvae so that some tiny proportion will be transported by the ocean currents and survive until they can find and colonize another whale carcass.

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