Report your invasive crab sightings

Mitten crab eggs

An egg-bearing female Chinese mitten crab from the River Thames in London, with around a million eggs attached to her underside

Principal Investigators

Project summary

  • Focus: To identify and report sightings of invasive crabs in order to prevent loss in biodiversity.

We are asking the public to report sightings of the more established Chinese mitten crab and new invader the Asian shore crab.

Chinese mitten crabs

Chinese mitten crabs are listed as one of the world's 100 worst invasive species. They cause problems by:

  • damaging fishing gear such as nets with their sharp claws
  • damaging river banks by burrowing into them
  • blocking intake streams from rivers, lakes and reservoirs
  • modifying natural habitats
  • competing with native species

The full extent of Chinese mitten crab distribution in the UK is unknown, so we are asking the public to help by reporting their sightings.

Mitten crab

Chinese mitten crabs can grow to the size of a dinner plate. They have distinctive setal mats on their claws that make them appear furry. They have a squarish body with four spines. © Aquatonics Ltd

Report your Chinese mitten crab sighting to the Mitten Crab Recording Project

Asian shore crab

Only a handful of sightings have been recorded in the UK so far, but the Asian shore crab is predicted to cause serious trouble if it becomes established. Where it has invaded northern Europe and the eastern coast of the USA, the Asian shore crab has displaced native shore crabs and destroyed shellfish populations.

Stopping them early is the only way to prevent an invasion in the UK, so if you spot an Asian shore crab, please report it.

Asian shore crab

The Asian shore crab is small (up to 4.5 cm across), has a distinctive square shaped shell (carapace) with three teeth on each side, and distinctively banded legs © Martin Burke

Biodiversity research

We are creating molecular and digital tools to explore undiscovered biodiversity

Invertebrate research

Our scientists are investigating the taxonomy, systematics and biodiversity of groups of invertebrates

Zoology collections

Our zoology collection has 29 million animal specimens and is rich in voucher, type and historical specimens