Zombie worms, also known as Osedax, are tiny worms that measure only about 1 to 3 inches long and are found deep below the ocean's surface. They got their name from their unusual feeding habits and were the first known creature feeding on the carcass of a gray whale in 2002.

Researchers have yet to fully understand how these sea creatures work, and how they extract nutrients from the bacteria. Some studies suggest that they digest them or use bacteria to digest fat and protein. Here's how these unique sea creatures feed on bones and carcasses of dead animals.

Zombie Worms Crave Bones, Carcasses of Animals That Falls at the Bottom of the Sea
(Photo : Wikimedia Commons/Fujiwara Y, Jimi N, Sumida PYG, Kawato M, Kitazato H (2019))
Close-up view of a Sunken whale skeleton vertebra colonized by Osedax braziliensis sp. n.

Zombie Worms Unique Diet

Unlike the zombies popularized in movies, books, or games, the zombie worms do not crave brains. According to Smithsonian Ocean magazine, Osedax worms crave bones and carcasses of dead animals.

These worms were first discovered living in bones of a rotting gray while that sank on the ocean floor, nearly 10,000 feet (3,000 meters) deep, in 2002. Scientists initially thought they were plants but when a deep-diving robot brought up samples of the specimen, they found that these are an animal that lives at the bottom of the sea.

The World Register of Marine Species said that since then, there are 26 specimens discovered. Upon analysis of the specimen, they found that zombie worms do not eat mineral bones directly as they would begin digesting fats within the bone instead. They secrete an acid from their skin that dissolves the bone so they could eat the fat and protein inside.

These worms have symbiotic bacteria living within them that digest the fat and protein, acquiring the nutrients they need. Scientists explain that by simply digesting the bacteria, nutrients are somehow transferred to them.

Although they are usually found in whale skeletons, extracting the final nutrients they could get, zombie worms do not discriminate among bones. Scientists found them on fish bones, and even in cow bones that were dumped from a ship. They drill to whatever bones they could find with symbiotic bacteria.

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Only Female Zombie Worms Do the Drilling

Zombie worms vary in size as some could be as small as an eyelash, while some are as long as a pinky finger. BRG reported that the ones visible in pink color are females because males are typically smaller and do not eat bones.

Only females drill bones since males live inside their bodies. A study reported seeing 111 males inside one female zombie worm alone. This eliminates the trouble of searching for a mate because their egg and sperm cells are right next to each other. Males can release sperm and disperse many fertilized eggs far and wide so that they could land on any fallen bone.

When males ran out of energy, they die completely. But another species of zombie worms also showed that they do it differently. Instead of living inside female zombie worms, they scrounge around the bones of carcasses until they find females then deliver the sperm to the female worms to fertilize their eggs.

This process is unique, intriguing, and terrifying at the same time. These bone-munching creatures are just one of the many deep-sea creatures that make the bottom of the sea floor more interesting.

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