Furry-clawed Chinese mitten crabs are spreading across the UK

Numbers of invasive Chinese mitten crabs are believed to be growing in the UK, causing damage to river beds and competing with native wildlife

By Chen Ly
13 October 2023



A Chinese mitten crab seen on the shore of the river Thames in London
Mike Lane/imageBROKER/Shutter​stock

People in the UK have been asked to report sightings of Chinese mitten crabs, an invasive species of concern whose population is thought to be growing.

Chinese mitten crabs (Eriocheir sinensis) are crustaceans native to East Asia named for their furry, brown, mitten-like claws. Their bodies can be a greenish grey to dark brown colour, usually growing to about 8 centimetres, with their legs extending to twice that length.

Over the past century, the crabs have spread around the world, including Europe and North America, where they are deemed an invasive species. They are typically found in freshwater habitats, such as rivers, canals and estuaries.

Chinese mitten crabs can wreak havoc on the environment by burrowing into river beds, blocking waterways and damaging fishing gear with their sharp claws. There are also concerns that they could eat fish eggs and outcompete native species for resources.

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