Sanibel Island is known for its plentiful shells, which visitors can learn more about at the Bailey-Matthews National Shell Museum. ( Selina Kok for The Washington POst/ )

Aviva Brickman, 11, had been on Sanibel Island, Fla., with her family for less than 24 hours and was already on her third shell hunt. This session was a little more official: a guided beach walk with a marine naturalist from the Bailey-Matthews National Shell Museum.

“Here’s a fighting conch I found,” said Aviva, holding up the swirled mollusk casing expertly identified by museum biologist Stefanie Wolf. “It’s fun to learn more about shells, but mostly I just like the different shapes and colors. Everything here is so different from the beaches at home. There are so many more shells — and palm trees.”

Home for Aviva is Potomac, Md., and she’s most familiar with Rehoboth Beach in Delaware. For this trip, in December, 12 people in her immediate and extended family were gathered on the island on Florida’s west coast partly because of its reputation as a world-famous shelling destination.

“There are spectacularly large amounts of shells here,” said her father, Aaron Brickman. “I hadn’t paid that much attention to the individual types, but after the talk, I have more of a trained eye. Like this spiny jewel box.” He held up a small, spike-covered white shell that we had just learned was a bivalve — two halves hinged with a strong, flexible ligament. “Now I see them everywhere.”

Meanwhile, 10-year-old Baoying Scott, from Eugene, Ore., was filling her bucket with a random assortment of shells, reluctant to choose favorites.


“I like looking at all of them, especially the ones with color,” she said.

Her mother, Ellen Scott, quickly added: “We’re going to collect and then sort. We can’t take them all home. In Oregon, we see mostly mussels and clams, so learning about the different shells here was quite amazing.”

Where those visitors saw beauty, I now envisioned a battlefield, or at least the aftermath of one, thanks to our pre-walk talk by leader Wolf. Like many people who stoop for occasional shells, I had never connected them with living animals, much less warriors of the sea.

But Wolf, who poured a big bag of shells on a table before the walk, explained and showed evidence of how, for instance, lightning whelks devour bivalves, crabs sloppily rip through shells to eat the mollusks living within, and other mollusks suck each other up. For instance, the holes you find in shells that seem to be nature’s gentle suggestion to turn a shell into jewelry? Actually, those holes are drilled by other mollusks after squirting them with a shell-softener enzyme to allow the predator access to the animal’s innards.

“The majority of shells eat each other,” Wolf said, matter-of-factly. “That’s how they die.”

Although death is not what one typically ponders while strolling the shoreline, the topic woke me up to the existence of mollusks — soft-bodied animals with no backbones, usually encased in a shell — the second most diverse group of animals on Earth. More than half of mollusks are gastropods, comprising 70,000 living species of marine, terrestrial and freshwater snails and slugs, according to the museum. About 20,000 are bivalves, such as clams, scallops and my favorite little colorful darlings, coquinas.

“Virtually no one has any idea where shells come from, including the people who live here” on Sanibel, museum executive director Dorrie Hipschman told me later, after I’d professed my ignorance. Since taking the helm at the museum in 2013, Hipschman has instituted the walks, offered daily, as well as regular “live tank talks” at the museum, which this year have increased to one nearly every hour the museum is open. She hopes to add more tanks in the future.

Baoying Scott, from Eugene, Ore., holds up a shell she found on Sanibel Island during a guided beach walk. ( Selina Kok for The Washington Post/ )

“Everyone comes to Sanibel loving shells,” she said. “We try to translate that love and passion into an understanding of the creatures that create the shells.”

After Wolf demonstrated the many ways mollusks kill each other, she admonished us to not kill them ourselves by collecting “live shells” — illegal in Lee County, which includes Sanibel. In 2013, the county adopted the most stringent shell-collecting rules in the state. Wolf showed us how to look for signs of life inside the shell, including tips for spotting live echinoderms — sand dollars, sea urchins and sea stars, which also are covered by the shelling law.

The museum, however, gets an occasional pass in the name of science.

“A couple times a month at low tide, we collect live shells for food for other shells,” Wolf said.

I had a clearer understanding of that a few hours later, when I caught up with Wolf again at the museum during a live tank talk.

“Every morning I come in, I can tell who has eaten who,” she said to the crowd while digging her hand into the sand to hold up a shiny lettered olive, a small mollusk that self-polishes to reduce friction while traveling through sand.

“It’s the fastest shell in the tank,” she said, placing it back in the water. “Look, it’s already digging.”

Wolf then pointed out a horse conch, a large predator. She reminded us to occasionally watch its progression as it moved across the floor of the tank by thrusting its foot against the bottom while lurching through the sand. By the end of her talk, it had reached the other side.

Daniel, a former Floridian, is a freelance writer based in the Netherlands. Her website is bydianedaniel.com.

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If you go
Bailey-Matthews National Shell Museum

3075 Sanibel-Captiva Rd., Sanibel

888-679-6450

shellmuseum.org

Admission is $11, $5 for ages 5-17, younger free. Guided beach walks leave daily from the Island Inn, located on the beach. Reservations required. Walk is $10, $7 for ages 5-17, younger free; includes half-off admission to the museum.

— D.D.