Bizarre Biology -- Bone-Eating Worms

In the category of creatures that would be hard to believe if invented in fiction as aliens, meet Osedax, commonly known as bone-eating worms:

Osedax

They're marine animals, a variety of tube worms, that live on the bones of decaying corpses such as those of whales.

They don't have a mouth, a digestive system, or an anus. Instead, they absorb nourishment more like plants than animals, through the magic of symbiosis. Adult females are sessile (fixed in place). They "settle on a bone, then secrete an acid through specialized root tissues to dissolve the bone's external layers in order to access the lipids within." Their symbiotic bacteria, which aid in processing nutrients for their Osedax host, live inside the worm's "vascularized root system which penetrates bone."

Even weirder is their extreme sexual dimorphism. Anglerfish, whose males atrophy into tiny lumps permanently attached to their female partners, seem ordinary by comparison. A female Osedax hosts 50 to 100 microscopic males (producing sperm while never developing past the larval stage) that live inside the tube surrounding her body. Therefore, when females spawn, the eggs emerge already fertilized.

Water-dwelling animals with roots? If we encountered something like Osedax on an extraterrestrial planet, we might have trouble recognizing it as an animal rather than a plant. Moreover, we'd probably assume it's a female reproducing by parthenogenisis until we had a chance to examine it closely and discover the microscopic males. What if similar tube worms on an alien world had evolved intelligence? Their biology and behavior would be so different from ours that communication with them would be very difficult -- rather like talking with trees on Earth, except that at least we share the same environment with our tree neighbors.

Margaret L. Carter

Please explore love among the monsters at Carter's Crypt.