Miyamoto N, Yamamoto T, Yusa Y, Fujiwara Y. 2013. Postembryonic development of the bone-eating worm Osedax japonicas. Naturwissenschaften 100:285-289.

The recently discovered deep-sea animals called bone-eating worms (Osedax japonicas) are specialized annelids that derive their common name from the niche in which they were found -- feeding on the bones of whale carcasses that had fallen to the ocean floor. The adult bodies ramify into whale bones and digest the organic material almost like fungi colonize wood. These whale falls only provide temporary homes for the worms however, so how do they disperse and inhabit other falls? In addition to the ephemeral nature of whale falls, there are successional waves of species that inhabit the falls, which makes for a relatively short window of opportunity for propagation.

Miyamoto et al. followed the development of juveniles into adulthood under laboratory conditions to examine dispersal and reproduction. After embryonic development in the female tube, Osedax larvae were shown to swim actively for extended lengths of time, settling on bones or female individuals of the same species. Larvae that settle onto bones then develop quite rapidly into mature female worms, while larvae that settle onto females metamorphose into males, which then reside in the tube of the female.

Miyamoto et al. suggested that the combination of rapid sexual maturity and attached dwarf males allows Osedax worms to inhabit and reproduce in their transient environment. Free-swimming larvae that actively swim for relatively long time periods then allow the worms to search vast distances to reach their specialized habitats.

(226 words)

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(posted Jan. 4 2016)