Overview

Comprehensive Description

Osedax worms are marine annelids closely related to the deep sea vestimentiferan worms. The sessile (i.e., fixed in one place) females bore into the bones of whale carcasses--and possibly bones of other vertebrates, as suggested by their documented colonization of experimentally submerged cow bones and of non-cetacean bones that had apparently been tossed off a boat as waste (Vrijenhoek et al. 2008). Sex in these worms is believed to be environmentally determined, with undifferentiated larvae that settle on bones developing as females and subsequent larvae that settle on females transforming into dwarf males. Mature females in at least some species maintain male "harems" and the number of males present grows rapidly as female size increases. (Vrijenhoek et al. 2008). The first Osedax worms were discovered by Rouse et al. (2004), who described two unusual new annelid species found on the bones of a dead Gray Whale (Eschrichtius robustus) off the coast of California (U.S.A.) at a depth of nearly 3000 meters. These worms were very abundant and each had four pinnule-bearing palps and a long oviduct on a trunk enclosed in a transparent mucous tube extending out of the bone tissue. Reaching into the bone marrow were vascularized “roots” extending from an ovisac that was filled with oocytes (developing eggs). The “roots” were packed with symbiotic bacteria of the order Oceanospirillales, a group of bacteria known for heterotrophic degradation of complex organic compounds. These unusual endosymbionts are likely responsible for the nutrition of Osedax worms (Goffredi et al. 2005). All visible worms were females, with trunk widths ranging from 0.2 to 0.5 mm. Associated with the trunk but attached to the mucous tubes of these 2 to 7 centimetre-sized Osedax females were dwarf males that were several orders of magnitude smaller than the females. The tubes of individual females contained numerous microscopic males--as many as 100 or more, with a male: female sex ratio of 17:1. (Rouse et al. 2004, 2008) Rouse et al. (2009) report on the first observations of spawning in Osedax (based on both field and laboratory studies) and describe the zygotes, embryogenesis, and larval development for two species from Monterey Bay, California. Cytological and molecular analysis of the spawned eggs of these Osedax revealed no evidence of the bacterial endosymbionts that female worms require for their nutrition, suggesting that the bacteria must be acquired later from the environment, as they are in other worms in the family Siboglinidae (Rouse et al. 2009).

As of 2009, the total number of known Osedax species was 17 or 18 (most of these not yet formally described). These species are distributed in both the Atlantic and Pacific Ocean basins and are found not only in the deep sea but also on whale carcasses as shallow as 34 meters (Pleijel et al. 2009 and references therein; Vrijenhoek et al. 2009). Vrijenhoek et al. (2009) present a phylogenetic analysis of all known formally described and putative Osedax species based on molecular data (from two mitochondrial and three nuclear genes). They also summarize key morphological features for each taxon and demonstrate close concordance between molecular analyses and patterns of variation in morphological traits, lending support to their conclusions about relationships within this group.

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Ecology

Habitat

Depth range based on 175 specimens in 5 taxa.
Water temperature and chemistry ranges based on 85 samples.

Environmental ranges
  Depth range (m): 125 - 2891
  Temperature range (°C): 4.231 - 12.546
  Nitrate (umol/L): 17.248 - 38.519
  Salinity (PPS): 34.372 - 34.480
  Oxygen (ml/l): 1.769 - 3.587
  Phosphate (umol/l): 1.198 - 2.759
  Silicate (umol/l): 31.485 - 113.540

Graphical representation

Depth range (m): 125 - 2891

Temperature range (°C): 4.231 - 12.546

Nitrate (umol/L): 17.248 - 38.519

Salinity (PPS): 34.372 - 34.480

Oxygen (ml/l): 1.769 - 3.587

Phosphate (umol/l): 1.198 - 2.759

Silicate (umol/l): 31.485 - 113.540
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records: 397
Specimens with Sequences: 328
Specimens with Barcodes: 312
Species: 20
Species With Barcodes: 18
Public Records: 328
Public Species: 18
Public BINs: 22
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Barcode data

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Wikipedia

Osedax

Osedax is a genus of deep-sea siboglinid polychaetes, commonly called boneworms, zombie worms, or bone-eating worms. Osedax is Latin for "bone-eating". The name alludes to how the worms bore into the bones of whale carcasses to reach enclosed lipids, on which they rely for sustenance.

Scientists from the Monterey Bay Aquarium Research Institute using the submarine ROV Tiburon first discovered the genus in Monterey Bay, California, in February 2002. The worms were found living on the bones of a decaying gray whale in the Monterey Canyon, at a depth of 2,893 m (9,491 ft).

Anatomy and physiology[edit]

Lacking stomach and mouth, Osedax rely on symbiotic species of bacteria that aid in the digestion of whale proteins and lipids and release nutrients that the worms can absorb. Osedax have colorful feathery plumes that act as gills and unusual root-like structures that absorb nutrients. The Osedax secrete acid (rather than rely on teeth) to bore into bone to access the nutrients.[2] Between 50 and 100 microscopic dwarf males live inside a single female and never develop past the larval stage.

Reproduction[edit]

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 that they are acquired after the worms settle on the bones.[3] In the adult, the bacteria are localised in the root-like structures that grow into the whale bone.[4][5] 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.

Male Osedax are microscopic dwarfs that live as "harems" inside the lumen of the gelatinous tube that surrounds each female. An individual female can house hundreds of these males in her tube.[6][7]

History[edit]

Following its discovery in 2002, the genus was announced in Science in 2004.[1]

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 (390 ft) 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), lived in very shallow waters compared to the previous discoveries.

In November 2009, researchers reported finding as many as 15 species of boneworms living in Monterey Bay on the California coast.[8]

Niche[edit]

The role of Osedax in the degradation of marine vertebrate remains is controversial. Some scientists[9] think that Osedax is a specialist on whalebones while others think that it is more of a generalist.[10] 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 marine vertebrate taphonomy. Burrows closely similar to those made by Osedax species have been found in the bones of ancient marine birds, suggesting that the genus may once have had a wider range of foods.[11][12]

Species[edit]

In popular culture[edit]

Osedax were mentioned in popular TV series Bones in episode 6 of season 6 aired on November 11, 2010 on the Fox Network.[13]

See also[edit]

References[edit]

  1. ^ a b G. W. Rouse, S. K. Goffredi, and R. C. Vrijenhoek (2004). "Osedax: Bone-Eating Marine Worms with Dwarf Males". Science 305 (5684): 668–671. doi:10.1126/science.1098650. PMID 15286372. 
  2. ^ "Bone-eating 'zombie' worms drill with acid". BBC News. 
  3. ^ G. W. Rouse, N. G. Wilson, S. K. Goffredi, 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 (3): 395–405. doi:10.1007/s00227-008-1091-z. 
  4. ^ Goffredi, S. K., Orphan, V. J., Rouse, G. W., Jahnke, L., Embaye, T., Turk, K., Lee, R. & Vrijenhoek, R. C. 2005 Evolutionary innovation: a bone-eating marine symbiosis. Environmental Microbiology 7, 1369-1378.
  5. ^ Piper, Ross (2007), Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals, Greenwood Press.
  6. ^ 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.
  7. ^ Vrijenhoek, R. C., Johnson, S. & Rouse, G. W. 2008 Bone-eating Osedax females and their "harems" of dwarf males are recruited from a common larval pool. Molecular Ecology 17, 4535-4544. doi:10.1111/j.1365-294X.2008.03937.x
  8. ^ Vrijenhoek, R.C., Johnson, S.B. & Rouse, G.W. 2009 A remarkable diversity of bone-eating worms (Osedax; Siboglinidae; Annelida). BMC Biology 7, 74 (13 pages). doi:10.1186/1741-7007-7-74
  9. ^ Glover et al. 2005; Dahlgren et al. 2006; Fujijura et al. 2006
  10. ^ Jones et al. 2008
  11. ^ Bone-boring worm once had a taste for birds. Osedax worms might have had a more-rounded diet 30 million years ago. Matt Kaplan. Nature, 6 December 2010. doi:10.1038/news.2010.651 http://www.nature.com/news/2010/101206/full/news.2010.651.html
  12. ^ Steffen Kiel, Wolf-Achim Kahl and James L. Goedert. Osedax borings in fossil marine bird bones. Naturwissenschaften. The Science of Nature. Published online: 20 November 2010. doi:10.1007/s00114-010-0740-5 http://www.springerlink.com/content/6vpv015338513652/
  13. ^ http://www.imdb.com/title/tt1628122/synopsis

Further reading[edit]

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