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5 Sensational Sea Snail Species

These Florida sea snails will slowly crawl into your heart

microcosmic_iNaturalist
© microcosmic/iNaturalist

Move out of the way, sea slugs, there’s a new charismatic critter on the block: the sea snail!

Sea snails are an extremely diverse group of marine gastropods that are found around the world. They can spend time on land, in saltwater or freshwater, be carnivores, herbivores or omnivores and vary in color, from ivory to brown, to vivid orange or pale violet.

Unlike sea slugs, you’re more likely to actually see a sea snail—and without having to venture to the ocean floor. They’re typically found in salt marshes or in shallow, coastal waters. Ever visited a beach and collected shells? Chances are, those are old sea snail shells!

So, what’s so great about sea snails? They are incredible mollusks that are an important source of food for marine wildlife, they provide shelter for other creatures that take up residence in their discarded shells (like hermit crabs) and, most importantly, they provide valuable insight to marine ecosystem health.

Ocean acidification and nutrient pollution are just two ways that sea snails can help gauge ecosystem health. Ocean acidification is caused by an increase in carbon pollution in our ocean, resulting in weaker shells in sea snails and many other shell-building organisms. Nutrient pollution, which can be from fertilizer runoff, stormwater runoff or sewage, is seen in many of the algae-eating sea snails and is a crucial indicator of the seriousness of pollution and the potential for harmful algal blooms in the region. Because they are so small, abundant and live in regions that experience a lot of fluctuation, scientists can easily monitor sea snails and quickly pick up on any ecosystem changes.

In the United States, Florida is a prime example of these pervasive water quality issues and is home to some sensational sea snails. Check out these five Florida sea snails:

Atlantic Moon Snail

Moon snail in shallow, sandy water
© Jarek Tuszyński
Also known as a “shark-eye,” the Atlantic moon snail (Neverita duplicata) has a smooth, swirling shell that ranges from gray to tan in color. They bury themselves in sandy flats, waiting for bivalves, like oysters, clams or even other snails. Once the moon snail finds a suitable snack, they can completely extend their bodies from their shell and envelop their prey, secreting acid that softens the bivalves’ shell until the snail can pierce through with its radula, a sort of “tongue” covered in thousands of little teeth, and suck up the soft, fleshy body within.

Crown Conch

Crown conch on Florida beach
© Robin Gwen Agarwal/iNaturalist
The crown conch (Melongena corona) is common in Florida’s estuaries, preferring warm, subtropical waters. While they are mainly found along the Gulf of Mexico, there’s a chance that these species may move farther up to the Atlantic coast as waters warm further north and other species migrate. As its name suggests, the crown conch has an elongated shell with a spiraled spire, which is the “top” or part of the shell that doesn’t contain the main body of the snail, with short peaks that give it a crown-like appearance. The crown conch varies in color from brown to purple to white and is carnivorous, eating bivalves, other snails and even some dead organisms. If there are a lot of crown conches in the area, and other species that typically live there are missing, it’s an indication of poor water quality. This can, in turn, affect the oyster and clam populations.

Florida Fighting Conch

Florida fighting conch
© microcosmic/iNaturalist
The Florida fighting conch (Strombus alatus) is most commonly found in Southwest Florida and gets its name from the sharp serrated spike attached to its foot, which is the flat, muscular organ that makes up the majority of the snail’s body. Surprisingly, the Florida fighting conch is an herbivore, eating algae or decaying, organic matter, and uses the serrated spike as a defense mechanism, thrusting around when they feel threatened. They like to stick to shallow, sandy waters and seagrass beds and only grow to about four to five inches in length. The Florida fighting conch also vary widely in color, ranging from orange to green to gray to brown.

Horse Conch

Horse Conch on Florida beach
© mkosiewski/iNaturalist
The horse conch (Triplofusus giganteus) is considered the largest sea snail in Florida and the United States, growing up to two feet in length. Although they are the official state seashell of Florida, they can be found all along the Atlantic coast, from Florida to North Carolina and in the shallow waters of the Yucatan Peninsula. If their size is any indication of their diet, the horse conch is carnivorous, preying on smaller sea snails and bivalves, smothering prey with their muscular foot. Their shells are bright orange that, interestingly enough, turns white/pale orange with age.

Marsh Periwinkle

Marsh periwinkle snails resting on grass stalks
© Will Parson/Chesapeake Bay Program
The marsh periwinkle (Littoraria irroata) is also found along the Atlantic coast in New York, Florida and Texas. They’re most commonly found in, you guessed it, salt marshes. Marsh periwinkles are a tiny species, averaging about an inch long, and have low, conical shells with a pointed spire. They are less flashy in color, typically grayish-white with red/brown dashes and are considered herbivores, munching on algae. What makes marsh periwinkles so interesting is that their eating habits adapt to the changing tide. At low tide, they crawl across the mud, searching for little bits of algae, but at high-tide, they must crawl up tall, stalks of grass in marshes to evade predators like the crown conch and blue crabs. Unfortunately, when the periwinkles escape up the stalks of grass, they pierce the plant and then eat the fungus that grows there—good for the sea snail, bad for the grass. Normally, the grass and sea snails can coexist, but with marsh habitats already facing numerous stressors with the changing climate, the already vulnerable marshes can be decimated by the small sea snail.

After learning about these sensational species in Florida, ready to make like a sea snail and take action for our ocean? If you’re a Florida resident, speak up and tell your legislators you support improving Florida’s water quality.

Not a Florida resident? No worries! You can still take action for our ocean by helping us, and sea snails, speak up on climate change. Contact your House representative to ask them to support legislation to protect our ocean from the effects of climate change.

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