Wild Wednesday - Hermit crab
Hermit crabs (scientific name Pagurus bernhardus) are crustaceans that are related to crabs, lobsters and prawns but unlike other crab species, hermit crabs do not have their own shell – they occupy empty seashells to protect themselves.
There are over 800 species of hermit crabs, 15 of which can be in the UK. They are commonly around one to four centimetres in length, on average weigh 7.3g and can live up to 30 years in the wild. Hermit crabs are native to the UK and found across the whole of the British Isles. They are not under any conservative threat.
Despite their name, hermit crabs are not solitary creatures and travel in groups of up to 100 individuals, some colonies can comprise of several hundred individuals as this makes it easier for them to find food and shells that suit their size.
Like many other species of crustaceans, hermit crabs moult so that they can grow. They will burrow under deep, damp sand and create a secluded, dark air ‘cave’ where they will undergo the shedding, this can take several weeks or even months.
As they grow, they need to switch to larger shells, which can lead to some interesting behaviours including shell “shopping” where they explore and try out different shells, in most cases, they will use the shells of dead snails, or whelks - squabbles for possession of an already occupied shell frequently occur
The best time to see them is at low tide, especially after a storm, when hermit crabs have been displaced from their home. The younger crabs can be found on rocky shores, throughout the year.
Like all British crab species, the hermit crab is a scavenger and will look for dead and dying forms of marine life to feed on In fact, they will eat just about anything they can find in the water that surrounds them, including small fish, invertebrates such as worms, plankton and any food particles that happen to be floating by.
Read more here: Hermit crab | The Wildlife Trusts