Osedax
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| Genus: | Osedax Rouse et al., 2004
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Osedax is a genus of deep-sea siboglinid polychaetes, commonly called zombie or bone-eating worms. Osedax is Latin for "bone-eating", the name alluding to how the worms bore into the bones of whale carcasses to reach enclosed lipids, on which they rely for sustanence. The genus was first discovered in Monterey Bay, California, in February 2002. They were found living in a decaying gray whale in the Monterey Canyon, at a depth of 2,800 m (9,100 feet) using the submarine ROV Tiburon.
Lacking stomach and mouth, Osedax rely on symbiotic species of bacteria to digest whale fat and oils and release nutrients that they can absorb. Osedax have colorful feathery plumes that act as gills, and unusual root-like structures that absorb nutrients. Between 50 and 100 microscopic dwarf males live inside a single female, and never develop past the larval stage.
Female Osedax worms have been observed spawning both in the wild and in laboratory aquaria (Rouse et al. 2009). Osedax rubiplumus can spawn hundreds of oocytes at a time. The worms' endosymbiont, the bacteria Oceanospirillales, was not observed in the spawned oocytes, which suggests they are acquired later on.[citation needed][1] In the adult, the bacteria are localised in the root-like structures that grow into the whale bone.[2] This worm appears to be highly fecund and reproduces continuously. This may help explain why Osedax is such a diverse genus, despite the rarity of whale falls in the ocean.
In late 2005, an experiment by Swedish marine biologists resulted in the discovery of a species of the worm in the North Sea off the west coast of Sweden. In the experiment, a minke whale carcass that had been washed ashore had been sunk to a depth of 120 m and monitored for several months. Biologists were surprised to find that unlike the previous discoveries, the new species, colloquially known as "bone eating snot flower" after its scientific name (Osedax mucofloris - a more accurate translation would be "slimeflower bone-eater"), lived in very shallow waters compared to the previous discoveries.
Craig Smith, a researcher in Hawaii, suggests that about half of Osedax species died out when 90% of the whale population was depleted by hunting at the end of the 19th century.[1]
The role of Osedax in the degradation of marine vertebrate remains is controversial. Some scientists think that Osedax is specialist on whalebones while others think that it is more generalist. This controversy is due to a biogeographic paradox: despite the rarity and ephemeral nature of whale falls, Osedax has a broad biogeographic range and is surprisingly diverse. One hypothesis advanced to explain this paradox is that Osedax are able to colonize a variety of vertebrate remains besides whalebones. This hypothesis is supported by an experiment involving cow bones suspended above the sea floor. A variety of Osedax species successfully colonized these bones. Osedax have also been observed colonizing terrestrial mammal bones mixed in with galley waste from a surface vessel. Other scientists have countered this hypothesis by pointing out how the cow bone experiment does not match any natural habitat and also the low probability of terrestrial mammal bones arriving at the ocean floor in significant quantities. They also point out other cases of food falls in which the remains disappeared too swiftly for Osedax colonization and the lack of any observed colonization in similar cases. The true role of Osedax in the degradation of marine vertebrate remains is important to understand because of its importance to marine vertebrate taphonomy.
Species
- Osedax frankpressi
- Osedax japonicus
- Osedax mucofloris
- Osedax roseus
- Osedax rubiplumus
- Osedax mcleanicus
References
- ^ G. W. Rouse, N. G. Wilson, S. K. GoVredi, S. B. Johnson, T. Smart, C. Widmer, C. M. Young, and R. C. Vrijenhoek (2009). "Spawning and development in Osedax boneworms (Siboglinidae, Annelida)". Marine Biology. 156: 395–405. doi:10.1007/s00227-008-1091-z.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Piper, Ross (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.
- G. W. Rouse, S. K. Goffredi, and R. C. Vrijenhoek (2004). "Osedax: Bone-Eating Marine Worms with Dwarf Males". Science. 305: 668–671. doi:10.1126/science.1098650. PMID 15286372.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - G. W. Rouse, K. Worsaae, S. Johnson, W. J. Jones, and R. C. Vrijenhoek (2008). "Acquisition of dwarf male 'harems' by recently settled females of Osedax roseus n. sp. (Siboglinidae; Annelida)". Biological Bulletin. 214: 67–82.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - A. G. Glover, K. M. Kemp, C. R. Smith and T. G. Dahlgren (2008). "On the role of bone-eating worms in the degradation of marine vertebrate remains". Proceedings of the Royal Society B. 275: 1959–1961. doi:10.1098/rspb.2008.0177.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - R. C. Vrijenhoek, P. Collins and C. L. Van Dover (2008). "Bone-eating marine worms: habitat specialists of generalists?". Proceedings of the Royal Society B. 275: 1963–1964. doi:10.1098/rspb.2008.0350.
See also
External links
- Press release describing discovery of Osedax
- BBC website - link to story about discovery of Osedax worms in the North Sea