Deep within the ocean, scientists and explorers alike have discovered all sorts of creatures almost unfathomable to our terrestrial minds. Giant octopus, electric eels, and anglerfish have all tickled our imagination over the past several centuries, and left us in awe of the capabilities of life.
A more recent discovery is that of the bone-eating worms. On one end of the worms are feathery plumes that act as gills to extract oxygen from the water. On the opposite end are root-like structures that dig deep below the bone surface. These newly discovered zombie worms were called Osedax, meaning “bone eating” in Latin.
Scientists from the Monterey Bay Aquarium Research Institute (MBARI) first discovered these underwater bone eaters in 2002 on a whale skeleton in Monterey Canyon. At 2,891 meters under sea level, these worms were found anchored into the bones of a whale carcass. The worms found by the scientists were of the species Osedax rubiplumus. The following two years, the scientists revisited the location and found that the Osedax rubiplumus worms were replaced by another species, Osedax frankpressi. Their results were published in 2004 in Science. Now dozens of Osedax species have been identified.
Though the name implies that these worms actually “eat,” they do not eat in the way familiar to us humans. Osadex worms have no mouths, stomachs, or anus. Instead they secrete acid to bore into the bones and rely on endosymbiont bacteria within the roots to harness nutrient such as collagen or cholesterol from the lipid- and protein-rich bones. The freed nutrients are then absorbed by the worms. These endosymbionts primarily belonged to the Oceanospirillales though many other species of bacteria were present.
Though Osedax species were first discovered in deep waters, many other Osedax worms have been found in waters all over the globe at different depths: Antarctica, the Mediterranean Sea, and the North Atlantic Ocean, to name a few. The endosymbionts these worms carry seem to vary based upon whether the worms were in deep or shallow seas and seem to be more location specific than host species specific.
The awe-inducing capabilities of Osedax species go beyond the fact that they feast upon bones. The only worms that colonize bones are female. Within these females is a harem of 50-600 microscopic dwarf males, making fertilization quite convenient. While females can spawn hundreds of oocytes at a time, none have been of found to contain endosymbionts, hinting that they may be acquired from the environment.
The symbiosis between Osedax and their microbial partners certainly make for a unique lifestyle. On top of their intriguing eating habits, Osedax worms bring along with them a harem of microscopic males and a mix of microbial symbionts, essential for keeping this species flourishing… as long as there are carcasses and skeletons in the mix.
