On a Tiny Caribbean Island, Hermit Crabs Form Sophisticated Social Networks
Hermit crabs have evolved sophisticated social strategies to exchange resources so that everyone benefits
by Ferris Jabr
Carrie Bow Cay is a tiny island in the Caribbean Sea, about 14 miles off the coast of Southern Belize. The island is so small—0.77 acres—that you can walk its entire perimeter in under 10 minutes. Scientists regularly visit Carrie Bow Cay to study coral reefs, mangroves and seagrass meadows, as well as the animals that live in these unique ecosystems.
When Sara Lewis and Randi Rotjan of Tufts University travel to Carrie Bow Cay, they spend most of their time underwater, examining corals. But they also wanted to make the most of their time on land, inbetween dives. So the biologists decided to study the behavior of Caribbean hermit crabs (Coenobita clypeatus), around 1,000 of which live on Carrie Bow Cay’s sandy shores.
Like all hermit crabs, Caribbean hermit crabs—which are the most popular pet variety in the United States—depend on other creatures’ shells for protection. Strip a hermit crab of its shell and you will see its soft, pink abdomen curled behind its head like a fern’s frond. Most hermit crabs favor snail shells, although some use the shells of bivalves, like clams and scallops, and others have made do with driftwood, stones and pieces of glass or plastic bottles.