Carcinus maenas reaches 10 cm. Atlantic cousin of Mediterranean C. aestuarii (in base). Hexagonal carapace green to yellowish or reddish, variable patterns. Cosmopolitan: native to the NE Atlantic but accidentally introduced in America, Australia, South Africa, Japan where it has become one of the most problematic marine invasive species. Extremely euryhaline: tolerates 0 to 35 PSU. Opportunistic omnivore. From 0 to 60 m.
