Exploring the variety of creatures found in British rockpools, with interesting facts, photos, videos and scientific I.D drawings that help you identify which marine creature you’ve found – this is the page for you if you love exploring rockpools.
The Common Hermit Crab – Eupagurus bernhardus
There are many species of hermit crab around the UK but the most common, is the aptly named, common hermit crab. Identified by its size, the large right claw which is covered in tubercles (small lumps on the shell) and the distinctive red and cream banded markings the hermit is easy to spot if you stand and wait patiently for them to run across the rockpool.
The common hermit crab grows up to 3.5cm in length – so not your biggest rockpool occupant.
Unable to make their own shells they instead live in empty sea snail shells, particularly those of whelks and periwinkles. They move in and out of these shells, swapping them out for bigger as they grow. Hermit crabs have incredibly tough pincers but a soft body which is protected by the sea shell home.
Found on rocky shores down to around 150m depth, they are plentiful along the UK coast. Opportunistic scavengers they walk across the seabed feeding on whatever plant or animal matter they find.
Usually observed amongst rockpools hidden inside their shell, their eyes, claws and legs protruding outwards if threatened they will retreat into their shell completely. When escaping a threat they will run backwards with their claws trailing and can move at impressive speeds for such small oddly shaped creatures.
If you gently lift a hermit crab out of the water and sit them in the palm of your hand you may discover you’ve found a brave hermit and be lucky enough to see them poke out their legs and stand up. If no legs appear after a minute you’ve found a ‘play dead’er’ so pop them back where you found them and move on.
When two hermit crabs meet each other, one may attempt to steal the others shell by forcibly evicting the current owner. The aggressor will size up the shell and determine if its larger than their current home and if it is – they will knock on the shell. This draws out its current owner (because apparently even in the world of hermit crabs its rude not to answer the door! ha) they then fight and the victorious keeps the larger shell.
Don’t forget – when rockpooling be gentle and light footed, don’t hold sea creatures for long and return them (and any rocks you move) back to where you found them.
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