The nature of things
SEVERAL house moves take the young hermit crab up the housing ladder to maturity and his final home. For Pagurus bernhardus, the most common hermit crab to be seen in British waters, a cockle or whelk shell provides an ideal des-res. When ‘between homes’—a dangerous moment that must be endured as briefly as possible— the growing hermit can be seen to be all legs and claws, of an orangey hue, at one end; the rest is a soft, spiralling body that will neatly furl itself into a discarded shell the next size up.
Common hermits are often found in rockpools, retreating back into the shell if feeling threatened or scurrying rapidly away, backwards, trailing its claws. One easy way to identify them is from the colouring as well as the obviously larger ‘right-hand’ claw.
Numerous hermits reside on British coasts, one of the most fascinating being Pagurus prideaux, with orange and purplish markings on its legs and a tenant on board: the cloak anemone, Adamsia palliata. These two creatures live together in symbiotic partnership, the anemone providing protection with its stinging threads, but achieving greater opportunities to feed by attachment to the mobile crab’s shell.
Diogenes pugilator, the south-claw hermit, also might be seen, and is easily identified by having its left claw larger than its right.
Illustration by Bill Donohoe