It's a worm. It's a snail. It's... Spider-Man?

Scientists have discovered a new species of a marine creature called a worm-snail (scientifically known as a vermetid) that shoots out a substance much like a web from our popular comic-book superhero.

Of course, there are some key differences: the shooting out occurs much more slowly — it's a snail, after all — and its "web" is a type of mucus. The mucus forms alongside its shell, where it collects micro-organisms to feed upon. When it's ready, it retracts the mucus, consumes it and then feeds on its catch. As well, the creature doesn't move: it picks a place, anchors down and does all its feeding and living from that one spot.

The new worm snail species is seen on its shipwreck home, with the mucus web it uses to trap food. The worm snail shell appears in this image as a blueish tube at centre; the web is behind it. (Rüdiger Bieler, The Field Museum)

"To us it's certainly something that we haven't seen before," Timothy Rawlings, co-author of the paper and chair of biology at Cape Breton University's School of Science & Technology, told CBC News.

While discovering a new species is always exciting for biologists, the team that made the discovery has some concerns: it's believed to be foreign to the waters off the Florida Keys, where it was found on a shipwreck that is part of an artificially created reef. That could spell bad news for the archipelago's already threatened coral reefs.

"There's this excitement of discovery … but the moment you look at an unusual or rarely studied invertebrate group, a whole new world opens up," lead researcher Ruediger Bieler of Chicago's The Field Museum said. "There are always new questions."

Threat to coral reefs

One of those questions is whether these worm-snails will move from their new habitat on the shipwreck to nearby coral reefs. If they do, they could reduce coral growth. Worm-snails are known to be hosts to some blood flukes. These are parasites to loggerhead turtles that can be found in the region.

And these little guys, with their shells measuring just five millimetres or so, are spreading fast.

When they were discovered in 2014, the new species — named Thylacodes vandyensis after the USNS General Hoyt S. Vandenberg where the snails were found — only three were attached to the shipwreck. However, a year and a half later there were thousands.

The newly discovered worm-snail is shown with its "foot" pulled into its shell. (Rüdiger Bieler)

"Potentially non-native worm-snails are coming into an area where we're having a tough time keeping the corals alive to begin with," Bieler said. "Between global warming and ocean acidification, and all kinds of other things, they don't really need more stress."

Using DNA testing, the biologists discovered that the species is native to the Pacific Ocean, though their exact location isn't known. This species has never been identified in the region before.

Now the researchers will attempt to find their local habitat.

"This … is an interesting find," Rawlings said. "It raises a lot of interesting questions like where it's come from, how it got there, where it fits into our understanding of the evolutionary history of the group and relationship to other species."

Worm-snails, which earned the moniker due to their elongated shells, are found around the world, with 80 being identified so far. But Bieler estimates there could be closer to 150 species.

Though concerned about the potential impact the species could have in the local ecosystem, Bieler has a particular fondness for his new discovery.

"Individually, these things are kind of cute," he said. "It's not their fault."