A new marine snail that would make the late great Jimmy Buffet proud has been discovered in the Florida Keys. The lemon-colored snail is named Cayo margarita after the Spanish word for “small, low island” and the tropical drink Buffet sings about in one of his biggest hits. The new and real resident of the fictional Margaritaville is described in a study published October 9 in the journal PeerJ.

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Marine smells are distantly related to the land-dwelling gastropods in gardens around the world. The margarita snails come from a group nicknamed worm snails, since they spend many of their lives living in one place. Worm snails also do not have a protective covering found in other snails called an operculum. This body part allows the snails to retreat further inside their shell and keep their bodies moist.

“Worm snails are just so different from pretty much any other regular snail,” study co-author Rüdiger Bieler tells PopSci. “These guys are sitting in the middle of the coral reef where everybody is out trying to eat them. And they’ve given up that protection and just advertise with their bright colors.”

Bieler is a marine biologist and curator of invertebrates at the Field Museum in Chicago who has spent 40 years studying the Western Atlantic’s invertebrates. Even after decades studying the region, these worm snails were hiding in plain sight during dive trips, largely because these snails are kind of the ultimate introverts.

Look closely. A margarita snail in the middle of a dead section of a large brain coral. CREDIT: R. Bieler.
Look closely. A margarita snail in the middle of a dead section of a large brain coral. CREDIT: R. Bieler.

Once juvenile worm snails find a spot to hunker down and they cement their shell to a hard surface never really move again. “Their shell continues to grow as an irregular tube around the snail’s body, and the animal hunts by laying out a mucus web to trap plankton and bits of detritus,” Bieler explains

Bieler and the rest of the international team of researchers came across the lemon-yellow snails in the Florida Keys National Marine Sanctuary and a similar lime-colored snail in Belize. Within the same species of snails, it is possible to get many different colors. There can also be color variations in a single population or even cluster of snails. Bieler believes that they may do this to confuse some of the coral reef fish that can see color so that they do not have a clear target. Some may use their hue as a warning color.  

The team initially believed that the lime-green and lemon-yellow snails were different species, but DNA sequencing revealed just how unique they are. This new yellow species belongs to the same family of marine snails as the invasive snail nicknamed the “Spider-Man” snail. This same team found these snails in 2017 on the Vandenberg shipwreck off the Florida Keys.

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The snails in this new Cayo genus also share a key trait in common with another worm snail genus called Thylacodes. The species Thylacodes bermudensis is found near Bermuda, and while only distantly related to their Floridaian and Belizean cousins, they have small colored heads and mucus that pop out of tubular shells. This might work as a deterrent to keep corals, anemones, and other reef fish from getting too close. The mucus has some nasty metabolites in it which might explain why these snails risk exposing their heads. 

The study and the new snails described in it help illuminate the stunning biodiversity of the world’s coral reefs, which are under serious threat due to climate change and the record warm ocean temperatures this summer

“These little snails are kind of beacons for biodiversity that need to be protected because many of them are dying out before we even get a chance to study them,” says Biler. 

It is also an important lesson in always looking right under your nose for discovery.

“I’ve been doing this for decades. We still find new species and previously unknown morphologies right under our feet,” says Biler. “This [discovery] was at snorkeling depth and in one of the most heavily touristed areas in the United States. When you look closely, there are still new things.”