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Spotting hermit crabs

Let's hear it for the Hermit Crab. The bargain hunters of the ocean. They don't aspire to Kevin McCloud and go building their own grand designs.  Hermit crabs are thrifty, they make use of those designs that molluscs have left behind.


Hermit crabs are my ultimate favourite. They've an eye for a perfect spiral and as they grow they move from first one then another second hand geometric home. Using shells of dogwhelks or periwinkles - whatever fits their soft body - they slide themselves in and two short back legs clamp themselves in place.


The oversize right pincer seems to cover the shell opening almost hiding them from view!


You have to be patient to see a hermit crab. They are masters of hide and seek. One quick glance in a rock pool and they very probably look like all the other periwinkles there. But remain still and quiet (they scare easily) and you may see a bubble pop out from under a shell and rise the the surface. Or you may spot one moving very slowly over the bottom of pool (this could be any mollusc though). 

One quick peep inside the opening and if it looks all slimy and snail like, you have to go back to hunting but if you see tiny crabs legs and a pincer, then well done - you have found one!


This is a fun video that I managed to capture when I last played hide and seek with a hermit crab.  I've only spotted three in ten years that’s how good they are at hiding! Have a look, maybe you can seek one too.


For more ideas on observation skills and inparticular geometry in nature check out The Smart Happy Project.

Lisa Lillywhite

The Smart Happy Project

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