Hermit crab

When: all year

Scientific name: Pagurus bernhardus

Gaelic name: aonaran crab

Size: Around 5 - 10cm along the shore, but can grow much bigger

Where: Along the shore in rockpools, burrowing in the mud. Shoreline at Limekilns can be a good place to find them

Hermit crabs are a welcome find on any shoreline or rockpooling trip. While the somewhat arduous trundling movement of a hermit crab seems like more hassle than it's worth, these little crustaceans need their shells to protect their soft bodies from harm.

 Despite their size, hermit crabs can be very feisty! When their shell starts to become a bit too snug, hermit crabs will venture out in search of a new abode. If the new shell that they desire is already occupied, the wee crabs will use their claws to rap on the shell in an attempt to evict the current occupier. If it comes to it, a particularly determined hermit will forcibly remove its opponent! The shells they inhabit tend to be those of periwinkles or dog whelks. The hermit crabs have evolved strange, twisted bodies that fit into the coils of the discarded shells.

 Traditionally, hermit crabs have been regarded as symbols of regeneration, transformation and protection. Although they are generally solitary creatures, it is little known that in some parts of the world, hermit crabs do form special relationships with another seabed dweller: the sea anemone. The anemones fix themselves to the hermit's shell, providing increased protection against predators and receiving a greater food suppply from the crab in return. This special relationship does not end when a hermit decides to upgrade shells either; hermit crabs have been known to pull their anemones off the old shell, fixing them onto the new home before shuffling away to show off thier new residence! Amazing footage of this kind of behaviour can be seen here: https://www.youtube.com/watch?v=dYFALyP2e7U

 Photo credit: Karen Williams, CoCoast volunteer.