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Seashore
Shore crab
Carcinus maenas
The crab you're most likely to meet on a British beach: dark green, quick, and always walking sideways.
- Size
- Shell up to 8cm across
- Look for it
- All year round
- Where
- Rock pools, under seaweed and stones, harbours and estuaries
My spotter's list
Scuttles sideways after you and raises its claws if you rush it. Move your pointer and see.
Good to know
Six things about the shore crab
WalkingSideways is quicker
A crab's legs bend sideways, like our knees bend forwards, so scuttling sideways is the fastest way for it to move.
ShellGrowing out of its shell
A crab's shell can't grow, so it climbs out of the old one and puffs up a new, bigger one. For a few days the new shell is soft.
ColourNot always green
Young shore crabs can be green, brown, orange or patterned with white. Older ones are often redder underneath.
TeethCount the points
Look at the front edge of the shell: a shore crab has five points on each side of its eyes and three between them.
FoodEats almost anything
Shore crabs eat worms, shellfish, dead fish and seaweed. That's why they come so readily to crabbing lines.
ClawsA new claw
If a crab loses a leg or a claw, it can grow a new one over its next few moults.
The real thing
Photos of the shore crab
Out and aboutHow to spot one
At low tide, gently lift seaweed at the edge of a rock pool, or look under stones in the mud of a harbour. Watch for a sideways dash.
Lend a handHow to help
Put stones back exactly as you found them, and if you go crabbing, keep the bucket shaded with only a few crabs in it, and let them go quickly.
Following youLadybird
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