worm

The Worm Osedax japonicus relies on the skeleton of a dead whale

Osedax japonicus is a species of bathypelagic polychaete tube worm that lives at great depths on the seabed and is able to sustain itself on the bones of a dead whale. It was first described in 2006 from a sunken sperm whale carcase near Kyushu, Japan

When a whale dies, its carcass falls to the seabed. Here it provides a feast for many deep-sea creatures. Worms such as Osedax japonicus make use of the bones when only the skeleton remains. The worms produce a branching network of “roots” that house symbiotic bacteria, which enable the worms to utilise the bones’ nutrient content.

The reproduction of Osedax japonicus has been studied. Female worms reach maturity at about six weeks. They secrete mucus to form a tube that surrounds their trunk. Male worms are minute by comparison with the females and they take up residence inside the tubes. The females spawn eggs and retain them in the mucus where they are fertilised by the males. Here they develop for a time before they swim out of the mucus as trochophore larvae. The larvae are then planktonic and can live for at least ten days in the open sea. It seems that if they settle on a suitable vertebrate bone they will develop into female worms but if mature females are already present on the bone, they will develop into males. The vast majority will fail to find any sunken bone.

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