Identification of mitten crabs
Mitten crabs can grow to a large size. The diameter of this plate is 25cm.
Mitten crabs are large crustaceans. River Thames specimens often have a carapace width over 84mm.
Diagnostic characteristics
The features that facilitate Eriocheir sinensis identification include:
- setal mats on the chelae
- quadrate (squarish) carapace
- frontal margin with deep central cleft and 4 spines
- 4 teeth on the carapace anterolateral margin
Distinguishing between the sexes
Male:
- narrow abdomen
- dense setal mats completely surround the claw
Female:
- broad abdomen to protect eggs
- setal mats do not completely surround the claw
Images of key features
The carapace of Eriocheir sinensis is quadrate (squarish).
The frontal margin between the eyes has a central cleft and four spines.
The antrolateral lateral carapace margin has four teeth.
Left chela of a male mitten crab. Dense setal mats (mittens) completely surround the claw.
Adult males have a narrow, V-shaped abdomen.
Adult females have a broad, U-shaped abdomen to protect their eggs.
Video of male and female mitten crabs
Watch the Museum's crustacean expert, Paul Clark, demonstrate the features that distinguish mitten crabs and see how crabs can be identified as male or female.
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