Meet The Newly Discovered Worm Snail That Thinks It's Spiderman


Stephen Luntz

Stephen has a science degree with a major in physics, an arts degree with majors in English Literature and History and Philosophy of Science and a Graduate Diploma in Science Communication.

Freelance Writer

worm snail

The mucus web released by Thylacodes vandyensis can be seen here above its "mouth". The worm-snail does not like attaching directly to artificial surfaces, but binds to mussels that have got there first. Dr Rudiger Bieler/The Field Museum

In the oceans off Florida, a worm snail species acts as if inspired by Spiderman. Thylacodes vandyensis shoots a web of mucus, trapping prey. It then swallows the slime, recycling it, and consuming the prey. Although this technique is used by many species, Thylacodes ups the slime quotient.

Scientists frequently declare newly discovered species “already endangered”. After all, anything previously unseen is probably rare. Thylacodes, on the other hand, may be more endangering than endangered. Its discoverers think it's new to Florida and may threaten coral reefs there – as if they didn't already have enough problems.


So far, however, Thylacodes has only been found at one location, the hull of the USNS General Hoyt S. Vandenburg after which it was named. Vandy, as it is known, is a retired naval vessel scuttled off the Florida keys in an effort to create new locations for corals to grow, bolstering the tourist industry. Vandy was once the world's largest artificial reef.

Dr. Rüdiger Bieler of Chicago's Field Museum has been studying worm snails for twenty years, telling IFLScience he was fascinated by creatures that crawl around in larval form, but as adults glue themselves to rocks and never travel again. “The snails have an extra pair of tentacles down near the base of their body, almost like little arms. These tentacles are what they use to shoot slime,” he said in a statement. When he saw a species he didn't recognize while diving on the fifth anniversary of Vandy's sinking, Bieler thought it deserved more attention, but found more than just a new species.

Bieler told IFLScience Thylacodes is larger than most worm snails. Moreover, while some other members of the Vermetidae rely primarily on filtering food particles through their gills, Thylacodes is one of those that derive most of their food from the slime webs, and consequently, produce far more mucus. Finally, most worm snails are fairly solitary creatures, while Thylacodes exists in extraordinary densities on Vandy's hull, leading to the production of great quantities of slime.

This is potentially a serious problem because worm snails and corals don't mix well. Bieler explained to IFLScience the slime appears to be “have a necrotic effect on coral, causing tissue death.” So far there is no evidence Thylacodes has spread to other shipwrecks, let alone natural reefs, but this may only be a matter of time. Thylacodes' DNA suggests its nearest relatives come from the Pacific, Bieler reports in PeerJ. He thinks it stowed away in bilge water or on the hull of a ship.


Even if Thylacodes can't grab space on established reefs, it could pose a threat to the region's active reef restoration efforts, if the lack of local predators allows it to thrive.

Thylacodes vandyensis appears to be giving Florida coral reefs the finger. Dr Rudiger Bieler/The Field Museum

  • tag
  • invasive species,

  • Spiderman,

  • worm-snail,

  • artificial reefs,

  • Vermetidae,

  • Thylacodes,

  • Florida reefs