Beast of the Month - WHITE-CLAWED CRAYFISH

June's beast of the Month is the WHITE-CLAWED CRAYFISH. These freshwater crustaceans (relatives of crabs and lobsters) are native to the UK's streams and rivers, but are disappearing from many. What is happening to this amazing creature?

Fantastic facts:

*Enemies: Herons, diving birds, large fish, otters, mink and signal crayfish.

*Breeding: September to November     *Size: Largest native UK freshwater crustacean

*Super-powers: active at night       *Latin name: Austropotamobius pallipes

But what are these animals and what can they do? White-clawed crayfish are:

Under threat

These small, gentle residents are the victims of bullying from a new and aggressive neighbour. The signal crayfish (pictured left), originally from America and introduced to the UK for their meat, are taking over streams and rivers, pushing out the natives as they go.

Signals are much larger and stronger than white-claws and compete for food and habitat. They are even thought to eat their smaller cousins if they can catch them! They are also spreading a fungal disease that the native white-claws have no defense against.

Freshwater champions   

White-clawed crayfish are particularly sensitive to poor water quality. Their stronghold in Cumbria has many clean, fast flowing streams free from the competitive signals. Their presence is used by conservationists to assess the health of river systems in an area.

Good Mums

Female crayfish carry a cluster of eggs beneath their tails, keeping them safe from predators. They begin to breed twards the end of summer and into autumn when the warmer water temperatures make them more active. They use the crevices beneath boulders and river banks in which to hide, keeping their young with them until May the following year. The eggs then hatch, and it can take around three years before the youngster grow to their full size.

Protected

White-claws are legally protected in the UK. Signals, on the other hand, are not so lucky, and many become delicious meals for conservationists out to catch them!