Two dazzling new snail species have been discovered by scientists diving in the Florida Keys and Belize. The two snails looked very similar, leading scientists to suspect they were the same species, but sequencing their DNA revealed big differences.
The Florida Keys are made up of a string of tropical islands that are home to the only coral reef system in the continental United States. Species found nowhere else on Earth can be seen here, including one of two new species of margarita snails.
What makes them so strange is that, unlike other snails who go mobile with their shelled homes, Vermetidae snails like the margaritas permanently cement their shells to a surface environment. This means they live a sessile life, a bit like tube worms, and have evolved to feed by laying out mucus webs that trap plankton and detritus.
The Florida Keys’ margarita snails went unnoticed for a long time because they are very small and good at staying hidden. When a team of scientists came across them, they thought they were looking at the same lemon-and-lime snails they’d spotted in Belize.
“Many snails are polychromatic – within the same species, you get different colors,” said lead author Rüdiger Bieler, curator of invertebrates at the Field Museum in Chicago, in a statement. “In a single population, even a single little cluster, one might be orange, one might be gray. I think they do it to confuse fish and not give them a clear target, and some have warning coloration.”
“Initially, when I saw the lime-green one and the lemon-yellow one, I figured they were the same species, but when we sequenced their DNA, they were very different.”
Using DNA sequencing, the team was able to place the margarita snails in a new genus they’ve named Cayo, taken from the Spanish word for a small, low island. The Keys margarita snail has been named Cayo margarita in honor of Jimmy Buffet’s Margaritaville, while the key-lime-colored snail in Belize is now called Cayo galbinus, which means “greenish-yellow”.
As for why they come in such dazzling shades of margarita yellow, the researchers suspect it may be a warning sign for hungry passers-by.
“Our thought is this is a warning color,” explained Bieler. “They have some nasty metabolites in their mucus. That also might help explain why they're able to have exposed heads – on the reef, everybody is out to eat you, and if you don't have any defensive mechanism, you will be overgrown by the corals and sea anemones and all the stuff around you. It seems like the mucus might help deter the neighbors from getting too close.”
Speaking of vibrant yellow things that pack a punch, have you heard of “margarita burn”?
The study is published in PeerJ.