Fear the Snail: inside the vicious world of the predatory gastropod

So snails suck, right? They’re boring and slow and they don’t do anything cool. Some of them make pretty shells that you find on the beach, but they’re pretty much slimy and gross and basically not interesting at all.

Said no one ever. At least not those who understand the world and daily life of snails. They’re tough, vicious, and sometimes terrifying in their adaptations to help them feed and protect themselves, especially in the case of marine snails, which can be as varied in shape, size, and color as the imagination.

“There are about 30,000 known species of snail,” said Gary Kidder, HMNS Discovery Guide and snail expert. “They’re a ‘Walt Disney’ class: if you can dream it, they can do it.”

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Slipper snail radula. Credit: Eric Heuple

Known in the science community as gastropods, meaning literally “stomach foot,” snails feed using a rasp-like tongue called a radula. Like most animals, the teeth vary from species to species based on what particular type of food the snail eats. In carnivorous snails, these teeth are like fish hooks that tear the flesh from their prey. Imagine having your skin licked off by a giant cat’s tongue! Terrible.

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The largest snail shell in the world, on display in the Strake Hall of Malacology.

Snails are not always small; they can grow to be massive. The Australian trumpet, or Syrinx aruanus, produces shells that can be as big around as your thigh. Measuring more than 30 inches in length, the record-holder for biggest snail shell in the world is on display in the Strake Hall of Malacology at the Houston Museum of Natural Science. It looks like you could fit a football inside this bad boy.

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Lightning whelk. Credit: DixieHwy

Predatory snails use some barbaric tactics to kill and eat their prey. There’s no saving a bivalve caught by a lightning whelkBusycon perversum (incidentally, the state shell of Texas). The lightning whelks pries open clams, wedging its soft foot between the halves of its shell, then it uses its radula to scrape out the clam a piece at a time. Kind of like a stranger kicking down your door and coming into your house to get you. Frightening.

That’s just the beginning. The moon snail, in the family Naticidae, bores into the shells of mollusks and crabs with its radula and an acid secretion. That’s right: acid. It melts a tiny hole through its prey and licks out its insides with its tongue. No thank you!

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Moon snail. Credit: Chris Wilson

To stun or kill their prey, many marine snails use some of the strongest venoms on Earth. The teeth in the radula of the geography cone, or Conus geographus, are modified to carry a venomous sting that disrupts insulin in its victims. Like a revolver loaded with up to twenty hypodermic needles (instead of six bullets), the cone snail harpoons its prey, sometimes with several stings in a matter of seconds.

“The venom gives you diabetes, basically,” Kidder said. “It makes you loopy. And if they’re able to hurt something our size, a fish, it’s usual prey, isn’t going to be an issue for it.”

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Conus geographus. Credit: Patrick Randall

The harpoon of the C. geographus can penetrate human skin and sometimes gloves and wetsuits depending on its size. A single sting from a Conus snail can cause muscle paralysis, difficulty breathing, and death. No antivenin exists; victims must be hospitalized until the venom wears off. Don’t pick these suckers up unless you’ve got comprehensive health insurance!

Scientists, however, see the cone snail’s venom as an opportunity for medicines, and are working to synthesize compounds from its unique chemical cocktail as treatments for a variety of diseases.

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Carrier snail. Credit: James St. John

Conus isn’t the only gastropod with potential benefit to humanity. The carrier shell, in the family Xenophoridae, Greek for “bearing foreigner,” uses a type of “concrete” to attach foreign objects to itself, reinforcing its own shell as it grows. The snail’s building media include other shells, pebbles, small pieces of coral, and in some instances human refuse like bottle caps. Scientists have even discovered new species from the shells attached to Xenophora.

“This is an aquatic saltwater snail that makes a cement that ‘dries’ underwater,” Kidder said. “If we can figure out how it does that, the economic possibilities are wild!”

So next time you see a land snail leaving a trail of slime, or a shell on the beach that once belonged to a marine gastropod, remember that in its own world, this slimy, slow-moving creature is a rock star.

Mala-whaaa? Discover the incredible world of mollusks in the Strake Hall of Malacology

One of the most awesome parts of working for a Museum (especially one as large as ours) is how many people you get to meet and work with – all with something different that gets them excited about science! It’s easy to celebrate your inner geek when you can find fellow geeks who you can geek out with in a geeky fashion while geekily reveling in unique parts of the Museum.

You could ask anyone here and they’d be able to tell you which part of the Museum brings this out in me: the Strake Hall of Malacology.

“Mala-whaaaa?” you may ask.

Malacology is the study of mollusks, an incredible group of creatures that includes octopi, scallops, and my favorite, snails (but more on them later). They’re invertebrates belonging to the phylum Mollusca, and there are over 85,000 species of them in the world!

These invertebrates all have three features in common but are otherwise extremely diverse. They have a mantle containing a cavity used for breathing and excretion; a radula, which is used for feeding; and the same structure to their nervous systems, with two pairs of nerve chords: one serving the internal organs and another for locomotion.

Mollusks are also able to use their internal organs for multiple purposes. For example, their heart and kidneys are used in their reproductive, circulatory, and excretion systems.

Mollusks are more varied than any other phylum. Think about it: squids, octopi, cuttlefish, nautili, clams, mussels, oysters, conch, slugs, snails — they all have many diverse species and yet they’re all still mollusks! And this is due, in part at least, to how long they’ve been around. While there’s still significant scientific debate about their precise lineages, we know that they’ve been around since the Cambrian period (541 to 485 million years ago). This has allowed them to diversify to fit in many, many niches all around the world — from the depths of the ocean to mountain tops.

Now for my favorite: SNAILS! Perhaps it’s because of my name (Gary, like Spongebob’s pet snail) but I think snails are really cool. They account for 80% of mollusks, and are perhaps the most diverse of them all. They’re found everywhere, in part because some have evolved to have gills while others have lungs.

But that’s not all! Some species with gills can be found on land, others with lungs are found in freshwater — with a select few even found in marine environments! They’re in ditches, deserts, large bodies of water and everywhere in between. Most are herbivores, but there are also omnivores and predatory snails. They’re also found in many sizes, from giant African land snails 35 cm in length to some just 1.5 mm long.

So come to HMNS to the Strake Hall of Malacology to learn everything there is about these marvelous mollusks!

Get your hands on science!

Seeing our dinosaurs up close is exciting – but getting your hands on science is an even more amazing experience. Which is why we try to bring you hands-on, educational activities that make you the scientist.

Visitors search for shark’s teeth in our Paleo Hall

Several mornings a week we have a volunteer on-hand in our Hall of Paleontology to help you experience the work of a paleontologist and malacologist.

Come by soon – you can help us sift through the shells and gravel collected by our teams in Bryan, Texas for fossils that are from the Eocene era, from species that lived over 35 million years ago. Help us separate the fossils – old snail shells, clams, mollusks, otoliths, coral and gastropods – and view them in tiny detail under the magnifying glass. Hold barracuda, manta ray and shark teeth in your hands, and help us to categorize them while you learn about ocean life both past and present.

Sift through shells, gastropods, and teeth
that are over 35 million years old

If sorting through our shell collection isn’t hands on enough for you, sign up to go on our family or adult day excursions with one of our curators. Go bird watching with Dan Brooks or collect your own shells on a malacology trip with David Temple. Sign up at hmns.org, and keep your eye open for future science trips.