This species of crayfish is the only native UK species. As the name suggests, the white-clawed crayfish has pinky-white claws; the body (carapace) is smooth but with a pitted appearance and a brown to olive colour. Their claws can feel rough on the upper side and can be a dirty white, almost pink colour on the underside, thus distinguishing white-clawed crayfish from their main threat; the introduced American signal crayfish (Pacifastacus leniusculus). Signal crayfish grow to much larger sizes and have distinctive red claw-undersides, although immature crayfish can be difficult to tell apart. The Turkish crayfish is another potential confusion species and is becoming more widespread in eastern England. The shape of the rostrum (tip of head) and presence of a row of spines on the carapace are the safest features for a positive ID for white-clawed crayfish. (Photos can be sent to NWT for identification).
Adult white-clawed crayfish moult once or twice a year and can grow up to 12cm in length from the tip of the head (rostrum) to the end of the tail (telson). Crayfish have many predators from dragonfly larvae to large fish such as pike, trout and eels. Herons and bitterns are also amongst their predators as well as the otter, mink and rat.