The Osedax roseus has no bones, mouth, stomach, eyes or ears, and yet it’s able to survive in marine environments nearly 10,000 feet deep. The worms are carrion eaters: Their skin secretes an acid that allows them to burrow deep into the bones of dead cetaceans, where bacteria living in their tendrils can feast on the fats and proteins within the whales’ bones.
Recent discoveries at Plymouth University in England have led researchers to conclude that the worm evolved much earlier than was first thought: almost 125 million years ago, well before the rise of modern whales, their chosen source of sustenance.
This bone-devouring beast might, in fact, be the reason scientists struggle with gaps in the fossil record; once the worms have their fill, nothing — not even bone — remains.
“[One hypothesis] was that the worms coevolved with whales, which would have placed them as emerging about 45 million years ago,” says Nicholas Higgs, a marine biologist at Plymouth University’s Marine Institute. “My study discovered traces of these worms in the fossils of old reptiles — plesiosaurs and pliosaurs — which sets the timeline much further back, to around 125 million years ago. That’s a gap spanning a tremendous amount of environmental change, which is amazing to see.”
Following the mass-extinction events that marked the end of the Cretaceous period around 66 million years ago, the Osedax roseus adapted to feed on the bones of turtles, until the rise of cetaceans allowed it once again to feast on pelagic leviathans.