The edible crab is the largest of the crab species commonly found around the British Isles
A mutant three-clawed crab hauled up in the pots of a local fisherman has been donated to Newquay's Blue Reef Aquarium.
He was caught by Phil Trebilcock, skipper of the fishing boat 'Loyal Partner'.
Phil was fishing 12 miles west of Newquay headland in water 25 fathoms deep and the crab was caught in an ordinary parlour pot.
The male edible crab has been nicknamed 'Tri' by aquarists which is Cornish for 'three'.
As well as a normal pair of fully functional pincers, the 20cm long edible crab also has a third set growing above his right claw.
Curator Matt Slater said: "It's very rare to find crustaceans with extra claws, very little research work has been done on this so no one really knows why this sometimes happens, it could be due to environmental factors or be a genetic mutation.
"Crabs, like other crustaceans, are capable of re-growing limbs and claws if they lose or damage them in a fight.
"It is also possible that somehow Tri's ability to re-generate lost limbs has got confused and, rather than replacing a missing set of claws, he's actually ended up growing an extra pair instead.
"Although the extra claws look impressive they can't actually function so he's no more dangerous to handle than any other crab. Except for the extra pincers he's in excellent condition and they clearly haven't prevented him from hunting and scavenging successfully," he added.
The edible crab is the largest of the crab species commonly found around the British Isles. It has characteristic large black tipped claws and a 'pie-crust' edge to the shell which make it easily identifiable.
Males can weigh up to three kilogrammes.
They are generally nocturnal, scavenging and foraging for food under the cover of darkness and adults are found down to around 100m depth.