Carcinus maenas ( Linnaeus, 1758 )

Wicksten, Mary K., 2012, Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371, Zootaxa 3371, pp. 1-307 : 235

Carcinus maenas ( Linnaeus, 1758)

( Fig. 55B)

Cancer maenas Linnaeus, 1758: 627 .

Carcinides maenas . — Rathbun 1930: 15, fig. 4.

Carcinus maenas . — Ingle 1980: 100, figs. 44, 44a, pl. 12b (extensive synonymy).— Williams 1984: 356, fig. 289. — Ricketts et al. 1985: 296, fig. 231. — Jensen 1995: 33, fig. 49. — Kuris et al. 2007: 642.

Diagnosis. Carapace about 0.75 times as long as broad. Front with 3 broad teeth, anterolateral margin with 5 strong teeth. Third maxilliped with anteroexternal angle not produced. Chelipeds slightly unequal, nearly smooth except for 2 ridges on upper surface of hand; merus short, carpus with broad internal tooth or angle. Pereopods 2–5 smooth, unarmed, dactyl of pereopod 5 lance-shaped, not forming swimming paddle. Male, female carapace length to 60 mm.

Color in life. Carapace dark green, bluish to reddish, sometimes China white; legs varying to yellowish white to tile white or violet; juveniles often more colorful, polymorphic in pigmentation than adults. Williams (1984: 356) gave a lengthy description of the cold patterns.

Habitat and depth. Bays, tide pools; among rocks, oysters, gravel or shells, intertidal to 200 m, but usually shallow. Tolerant of low salinity.

Range. Northumberland Strait to Virginia in North America; Kvaenangen, Norway , Baltic Sea and North Sea to Mauritania . Introduced into San Francisco Bay , California and Willapa Bay, Washington; also Australia, Burma , Red Sea , Madagascar, India , and Ceylon. Type locality Marstrand north of Goteborg, west coast of Sweden .

Remarks. Hardy and a prolific breeder, the green crab easily can be spread by human activity. It is a predator on clams and oysters, and thus is considered a pest by fishermen. The range of this species is spreading rapidly.