If you see a snail walking across the touch table in our Splash Zone exhibit, look closer—it’s a hermit crab in a discarded snail shell! Hermit crabs wear shells to protect their soft abdomens—which are asymmetrical and curved to fit the spiral shape of their shell. Like all crabs, hermit crabs are decapods—they have five pairs of legs, including a pair of claws. One claw is much larger than the other—the hermit crab uses it for defense and food shredding; it uses the smaller claw for eating. The second and third pairs of legs help the crab walk, and the last two pairs hold the hermit crab in its shell.
Hermit crabs are abundant in tide pools. If you visit tide pools, it’s important to follow tide pool etiquette—look, but don’t disturb or collect, which is illegal on many shores. Since the number of empty shells in a tide pool ensures the survival of hermit crabs, please leave all empty shells where you find them. And take care of yourself—remember that rocks in the tide pool are slippery. Face the ocean—unexpected large waves can easily sweep you into the water.
Hermit crabs prefer certain shells. Pagurus samuelis, a common tide pool hermit crab, prefers the shells of black turban snails.
Hermit crabs move into larger shells as they grow—fighting with other hermit crabs for the shells if necessary—but they don’t harm healthy snails.