Bone-eating marine worms: habitat specialists or generalists?

We are happy to see the acknowledgement by Glover et al. (2008) ‘that absence of evidence cannot in itself lend support to the theory that Osedax are exclusively whale-fall specialists’. Jones et al. (2008) reported that bone-eating marine worms of the genus Osedax will grow on cow bones deposited at various depths in Monterey Bay, California. The report clearly stated that cow bones suspended from a short ‘tree’ made of PVC pipe presented an ‘unlikely resource for marine worms’. Nevertheless, several Osedax species colonized the cow bones, grew and produced mature eggs, an indication that the worms do not require substances found only in cetacean bones for settlement cues or nutrition. Osedax employ a branching ‘root’ system that hosts heterotrophic bacterial endosymbionts to extract organic compounds such as collagen and cholesterol from bones (Goffredi et al. 2005, 2007). Because animal tissues are rich in these compounds Osedax may be capable of living on a variety of vertebrate bones and other substrates. Fujikura et al. (2006) reported that Osedax japonicus also grew on ‘tainted spermaceti’, a waxy substance found in the head of a sperm whale. Indeed, some Osedax species are plastic in their substrate requirements