Genetic mutation

Wainess added, "I've only seen this specimen before. It's probably some kind of genetic mutation." He says crabs have the ability to regrow limbs or claws if they lose one during a fight. The aquarium team says Claudette's ability was disrupted, and the crab grew an additional claw in place of the lost limb.

Edible crabs constitute the largest proportion of all crab species in England. They use black-tipped claws to capture and devour prey.