Hermit Crabs (Pagurus spp.)

Description: There are many species of hermit crabs found in the tide pools of Haystack Rock. Their body is usually a dark green or brown color, possibly with bands of white, red, blue, or green on the legs. Overall size at first glance will be heavily impacted by the size of the shell they choose to inhabit but the hermit crabs themselves are between 1.5-4 cm. These creatures are easily startled; the slightest of movements will have them curling their legs up inside their shell to hide from predators.

Habitat: Hermit crabs like to live in the protected waters of tide pools, typically hiding underneath rocks or algae.

Diet: Hermit crabs will eat whatever they can get their tiny claws on from small fish, worms, or decomposing plant or animal matter. They’re able to sense nearby food with their very long antennae.

Tide Pool Tidbits:

• While the primary defense mechanism of hermit crabs is to hide in their shell, some will completely abandon their shell to escape predators. Sometimes it’s best to drop the extra weight from their shell to scamper away faster and get out of harm’s way. 

• Hermit crabs don’t grow their shells; instead, they find abandoned shells left behind after snails die to move into. They can even smell dead and dying snails and follow to potential new homes. As hermit crabs grow, they continuously need to find bigger and bigger shells to live in. This can lead to fights to the death if multiple hermit crabs want the same shell!

• Sometimes, it’s possible to find hermit crabs with barnacles either growing on their shell or on their legs.

• There are over 500 species of hermit crabs in the world! Not all of them are in the Pagurus genus but most of the ones in the Pacific Northwest are.

References: Seattle Aquarium, Walla Walla University