Carcinus maenas

Overview

MarLIN describes a broad carapace up to about eight centimetres across, with five teeth on each side and three lobes between the eyes. Colour varies among green, orange and red. Males have a triangular folded abdomen and females a broader, rounded one.

The crab eats algae, molluscs, arthropods, worms and carrion. It tolerates a wide range of salinities, occurs in estuaries and salt marshes, and grows by moulting.

NOAA Fisheries reports the first confirmed Alaskan observation on Annette Islands Reserve on 19 July 2022, made by the Metlakatla Indian Community. Larvae may spread on currents, and invasive populations can damage eelgrass and compete with native animals. The record documents occurrence, not an exact introduction date.

Origins & earliest records

The Linnaeus 1758 attribution records scientific naming, not evolutionary origin; original type material was not examined for this profile.

Evidence & interpretation

Based on the MarLIN species account and a NOAA Fisheries page on invasive green crab in Alaska.

Selected bibliography

Documented works and useful reading. This is not a list of every appearance.

1. 01

   Common shore crab (Carcinus maenas)

   · 2008

   Selected bibliography; MarLIN species account for morphology, diet, habitat and classification.

2. 02

   Invasive Green Crab: Look Out

   · n.d.

   Selected bibliography; NOAA Fisheries page for the 2022 Alaskan record and invasion impacts.

Family, evolution & connections

Taxonomic classification

A hierarchy of classified groups, not a chain of direct ancestors.

Source note: Only family and species placement given in the MarLIN account are recorded; higher ranks were not established from the packet.

1. FamilyCarcinidae
2. SpeciesCarcinus maenas Linnaeus, 1758

References

Sources supporting this profile. Linked pages have their own scope and editorial standards.

1. Institutional species accountCommon shore crab (Carcinus maenas)Research access: 2026-10-07
2. Government agency web pageInvasive Green Crab: Look OutResearch access: 2026-10-07

Image credits

A sourced illustration has not yet been added. This gap is included in the coverage record.