Bone-eating worms of the deep sea

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Osedax, Latin for ‘bone-eating’, a genus of deep-sea polychaete worms have sedentary females that bore into bones of whale carcasses from which they derive nutrition. This, an undescribed species known as ‘orange collar’, was collected at 600 m from Monterey Bay, California.

When whales die, their enormous floating bodies provide food for sharks and other surface scavengers. Once the rotting flesh and bones sink to ocean floor depths of 2000–4000 metres where they settle, they are known as whale-fall. Communities of animals congregate on and around whale-fall, and slowly eat and break them down over a period of years.

Scientist Dr Greg Rouse, now an Honorary Research Associate at the South Australian Museum, was part of a team of scientists to discover a new genus of whale-fall invertebrates known as Osedax. The two species Osedax rubiplumus and Osedax frankpressi are found at depths of approximately 3000 metres, and appear as delicate red plumes emanating from the surface of whale-fall bones. In addition to the red external component, each worm has a root-like structure that invades the bone marrow. A very unique, mutually beneficial relationship known as symbiosis allows Osedax to derive nutrition from the marrow. Each individual hosts bacteria known as Oceanospirillales, which break down marrow fats and other bone materials into smaller compounds which nourish the worms.

Visible Osedax worms on whale-fall are all female and are usually a few centimetres in length. The males are comparatively very tiny, and exist only as ‘sperm machines’ housed within the egg sac of female worms.

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A colony of hundreds of ‘orange collar’ Osedax on the phalange (finger bone) from the flipper of a grey whale recovered at 600 m from Monterey Bay, California. This colony was maintained in the laboratory in order to study their reproductive behaviour. 

 Osedax worms are related to other species of deep-sea worms that occupy oxygen– and nutrient–poor sites thousands of metres from the sea surface. 

This research was published in the journal Science*.  

 

*G. W. Rouse, S. K. Goffredi, and R. C. Vrijenhoek (2004). Osedax: Bone-eating marine worms with dwarf males.  Science (30 July 2004) 305 no. 5684: 668–671. 

The project was funded by the David and Lucile Packard Foundation and the South Australian Museum.