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White-clawed crayfish

Scientific name: Austropotamobius pallipesWhite-clawed crayfish

Country: Originally widespread in Europe, populations are decreasing.

Continent: Europe

Diet: Omnivore – snails, worms, insect larvae, small fish, algae, leaf litter and calcified plants. Diet varies as the crayfish ages.

Food & feeding: Omnivore

Habitats: Rivers, streams, lakes

Conservation status: Endangered

Relatives: Lobster

Description: Looking like mini lobsters, one of the first things you will notice are the large front claws. These are used for displays during the breeding season, as well as being a useful tool for collecting food. These claws give the white-clawed crayfish its name. Their bodies are an olive brown colour, but the underside of the claws is a pale pink-white. They are the largest freshwater invertebrate in the UK and play an important role in rivers and lakes. They help to keep water ecology stable and are a food source for creatures such as otters and herons. Generally, adults grow to a maximum of 15cm and they can live over 10 years.

Lifestyle: Despite their claws, white-clawed crayfish are shy animals, hiding under rocks and roots in rivers and lakes. They are nocturnal and can best be seen in shallow water during the evening. Important to our waterways, they are seriously under threat from the introduced American signal crayfish. The signal crayfish out competes the UK species for resources, but also carries a disease known as the crayfish plague – harmless to the signal crayfish but deadly to the white-clawed crayfish.

Family & friends: A solitary species, individuals only seek out others during the breeding season (September to December).

Keeping in touch: When crayfish meet other individuals they use their antennae, claws and general body movement to communicate. Males become very territorial during the breeding season and they display their claws.  They also send out warning messages by releasing urine when competing males enter their territory.

Growing up: Females typically start to produce eggs after 3 to 4 years (when carpace length reaches 24mm or more). They make good mothers… in the beginning. Producing between 20 and 160 eggs per brood, the mother protectively carries the eggs under her tail for the entire winter. Once hatched the young hold on to the mother until they are ready to survive on their own. However, once the young are ready to leave, it is a race to get away from mum who will try and eat them!

Conservation news: Up to 95% of white-clawed crayfish populations in the UK have been lost in recent years – mostly because of the American signal crayfish and the crayfish plague. Bristol Zoo Gardens is working with the South West Crayfish Conservation Group to move threatened populations to safe areas in the wild. An exciting captive breeding programme is also being run at Bristol Zoo Gardens in an effort to stabilise the rapidly declining wild populations. Click here and see our conservation projects page for more information on the project, and how you can help prevent the spread of disease.