Nature & Environment

'Zombie' Worms: Terrifying Creatures that Spit Acid and Munch Whale Bones

Catherine Griffin
First Posted: May 01, 2013 03:01 PM EDT

Zombies exist--as long as you consider these sea worms to actually be "zombies." The bone-munching creatures thrive on the dead carcasses of whales where they spit acid to burrow into the remains. Now, researchers are learning a little bit more about these so-called "zombie worms."

The worms themselves were first discovered in 2002 off of the coast of California in the decomposing remains of a gray whale on the ocean floor. Their real name is Osedax, which is derived from the Latin for "bone eating." True to their name, these creatures live within the bones of large vertebrate skeletons where they feed on the nutritious oils within.

In addition to their relatively creepy choice of diet, zombie worms also have a few other strange attributes. Unlike many species of animals, female worms are actually much larger than the males. By "much larger," we mean that 50 to 100 males often live inside of one female. The male's sole purpose seems to be as a sperm producer, according to National Geographic.

Along with their choice of diet and their weird breeding behavior, these worms also have the ability to spit acid--even though they technically lack mouths. In this latest study, the researchers examined these worms as they used a "proton pump" to secrete acid onto the bone. Similar acid-secreting enzymes exist in all other organisms, such as in human kidneys to handle blood and urine functions.

"The acid presumably allows the worms to release and absorb collagen and lipids that are trapped in bone," said Martín Tresguerres, one of the researchers, in a news release. "This model is remarkably similar to how mammals repair and remodel bone; however, Osedax secrete acid to dissolve foreign bone and access nutrients."

So how do these worms even digest bone if they have no mouths? Bacteria actually live symbiotically within the worms and are involved in this process. However, scientists still aren't exactly sure how the digestion works. Some evidence suggests that the bacteria metabolize bone-derived collagen into other diverse organic compounds and the worms subsequently digest the actual bacteria for their own nutrition.

If these traits weren't strange enough for you, there's also the fact that researchers are unsure exactly how the worms make it onto the whale skeletons in the first place. It's possible that they're transported by other fish, or travel on currents. Currently, scientists are working on understanding a bit more about these bizarre creatures.

The latest study was published in the journal Proceedings of the Royal Society B.

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