Common hermit crab

The common hermit crab is one of the sea’s most lovable recyclers. Unlike most crabs, its curly tail is soft instead of hard, so it needs somewhere snug to keep it safe. Its clever answer is to borrow an empty snail shell and wear it like a cosy home, carrying it everywhere it goes. You will find these reddish little crabs in rock pools and on sandy seabeds around Europe’s Atlantic coast.

The trouble with a borrowed home is that the crab keeps growing, and one day its shell becomes too tight. So the hermit crab goes house-hunting. It finds a bigger empty shell, checks it over carefully, then quickly tucks its soft tail inside. Old shells left behind by periwinkles and whelks make perfect new homes for the crab as it gets larger.

At the front, a hermit crab has two pincers, and the right one is much bigger than the left. When something worrying comes near, the crab pulls itself deep inside its shell and blocks the doorway with that big claw, like shutting a front door. Its pincers also help it pick up food and clamber over rocks and gravel on the seabed.

This little crab is not fussy about dinner. It is an omnivore that scavenges worms, tiny shellfish, seaweed and scraps left on the seabed, day and night. By eating up leftovers, it helps keep its underwater world clean and tidy. Hermit crabs shuffle busily across the bottom of the sea, always sniffing out where their next meal might be hiding.

Sometimes a hermit crab shares its shell with a special guest. A sea anemone may settle on top, riding along like a gentle passenger. The anemone’s waving arms help keep the crab safe, and in return it catches drifting scraps of the crab’s food. The two live together as friendly neighbours, quietly helping each other out as they travel the seabed.