Tuesday, June 9, 2015

Tracks in the Tidepools

Hermit Crabs have curved abdomens which are soft, unlike most crustaceans which have hard, calcified abdomens. Because of their soft abdomens, the hermit crab is vulnerable to predators and seeks protection in the form of salvaged, empty seashells. The hermit crab will typically select the shell of a sea snail into which its entire body can retract for protection.


Hermit Grab in the Tidepool
Photo Courtesy of Carolyn Propst

As you might guess, as a hermit crab grows it gets too big for its salvaged shell and must look for a larger one. The competition for shells can be vigorous when there are lots of hermit crabs of the same size vying for an available shell. When the hermit crab finds a new shell it will leave its current shell to 'try on' the new shell. If it fits, it will stay in the new shell leaving the old shell for a smaller hermit crab to make the shell its home. If it doesn't fit, the hermit crab returns to its shell and continues the quest for a empty shell that is the perfect fit!

Tracks in the tidepools are a great way to find a hermit crab. As the crab moves along the sand it will sometimes leave a track in the sand - if you follow the track to the ends the hermit crab is bound to be at one end or the other!


Hermit Crab Tracks in the Sand
Photo Courtesy of Carolyn Propst

Next time you are tidepooling at Haystack Rock, take some time to look for a track that is sure to lead to the discovery of a hermit crab. HRAP Interpreters are on the beach every day at low tide and are happy to answer any questions you might have!


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