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Inhabitants of Oregon Tidepools: Hermit Crabs

What would you do with a soft tail?

A hermit crab slips its soft abdomen into an empty shell. The crab is protected while nestled deep inside, sometimes nestled too deep to see. The delicate abdomen is gently curved to fit snuggly in the shell; trying to pull the crab out could rip it in half.

Slender, jointed legs and long, delicate antennae peek out (up to an inch) from beneath the edge of the stubby spiral of the black snail shell, along with short eyestalks and small-but-busy mouthparts. Undisturbed, hermit crabs jostle and jerk along the tidepool bottom and through the seaweeds: slow moving snail shells are probably actually snails, fast moving snail shells are probably hermit crabs inside old snail shells.

As the hermit crab grows, it needs larger shells. A large hermit crab in a too-small shell won’t be able to withdraw all the way into the shell, leaving it exposed to predators and thieving relatives. A small hermit crab in a very large shell may be able to withdraw so far that you wouldn’t be able to see it—even a shell that looks empty may not be.

Leaving shells on the beach leaves more hermit crab housing!

A hermit crab is a hermit crab—right? 

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