On the outside, it looks like an elephant tusk. Inside, its tapered, jet-black body slithers and flops as if it just slipped out of a Jell-O mold.
It’s not actually a worm at all, but a huge, squishy bivalve that can grow to 5 feet long without actually eating anything!
Meet the giant shipworm.
After 200 years of eluding scientists and leaving behind only hollow tubes buried in mud as clues, this clam cousin was finally bested by a group of researchers working in a lagoon in the Philippines.
But when they pulled the giant shipworm from the mud, what they found raised more questions than answers.
Most shipworms are small and feed on rotting wood, which explains why they chase shipwrecks. And most giant versions of animals can be partially explained by their oversized dinners.
But the shell of the giant shipworm grows right over its mouth, and its digestive system is shriveled from lack of use.
A scientist removes the top of a shipworm shell. (Photo by Marvin Altamia)
It’s not eating wood. It’s not eating mud. In fact, it doesn’t seem to be eating anything at all! So how does it grow into the stuff of our sci-fi nightmares?
If you’ve ever smelled rotten eggs while walking through a swampy area, you’ve smelled hydrogen sulfide, which is the gas that gets released when wood or other organic matter rots. When the researchers looked at the gills of the giant shipworm, they found bacteria that consume hydrogen sulfide, and in turn, make food for the shipworm.
Scientists think that this ability to get energy from hydrogen sulfide is the trick used by the very first life on this planet. Single-celled microbes at the hydrothermal vents in the deepest reaches of the sea evolved into multi-celled animals because they were able to figure out how to use the gas plumes to make food.
The mouth of the giant shipworm. (Photo by Marvin Altamia)
Now scientists think the giant shipworm got its girth by harnessing the same superpower, so it’s possible it has something to teach us about the origin of life on Earth.
But one thing's for sure: This is a clam you won’t be slurping down raw anytime soon!