What is a White-clawed crayfish

The White-clawed crayfish (Austropotamobius pallipes) is the UK’s only native crayfish species - the White-claws originate from the UK whereas other crayfish species have been introduced from other countries. Since the 1970s there has been more than a 50% decline in the areas where White-claws occur in England and Wales and they are still declining rapidly both in numbers and in the places where they are found.

The White-clawed crayfish is one of our largest freshwater invertebrates and they grow up to 12 cm long. They are omnivorous so they are not fussy eaters and eat everything from other invertebrates to carrion and water plants.

White-claws have large pincers (claws) that are coloured cream or rosy white on their underside, and it is these distinctive claws which have given White-claws their name. The carapace is generally brown to olive in colour with a pitted appearance. However, all colour variations have been observed, including blue and red White-claws. They are nocturnal creatures and aren’t very active during the winter, which means that this secretive invertebrate is rarely seen.

Red White-claw and White-claws showing the usual brown colouration. © Nick Whatley

They have important roles in the freshwater environment because of their diet and as well as providing food for other animals such as fish, herons and otters. They are also important indicators of good water quality as they are intolerant of pollution. To find about more about the life cycle of crayfish click here.

You can also find out more with Bill Oddie as he goes in search of White-clawed crayfish in these BBC shorts, Rare Natives and Crayfish Whisperer.