European Green Crab

Carcinus maenas has a carapace up to 60 mm (2.4 in) long and 90 mm (3.5 in) wide, but can be larger outside its native range, reaching 100 mm (3.9 in) wide in British Columbia. The carapace has five short teeth along the rim behind each eye, and three undulations between the eyes. The undulations, which protrude beyond the eyes, are the simplest means of distinguishing C. maenas from the closely related C. aestuarii, which can also be an invasive species. In C. aestuarii, the carapace lacks any bumps and extends forward beyond the eyes. Another characteristic for distinguishing the two species is the form of the first and second pleopods (collectively the gonopods), which are straight and parallel in C. aestuarii, but curve outwards in C. maenas.

Carcinus maenas is native to European and North African coasts as far as the Baltic Sea in the east, and Iceland and Central Norway in the north, and is one of the most common crabs throughout much of its range. In the Mediterranean Sea, it is replaced by the closely related Mediterranean green crab species C. aestuarii.

In its native range, European green crab is mostly used as an ingredient in soups and sauces. However, the closely related Mediterranean green crab (C. aestuarii) has a thriving culinary market in Italy, where fishermen known as moecante cultivate soft-shell green crabs (moeche in Venetian, moleche in Italian) and sell hard-shell crabs for their roe (masinette). Several groups in New England have successfully adapted these methods to produce soft-shell green crabs from the invasive species.

Carcinus maenas can live in all types of protected and semiprotected marine and estuarine habitats, including those with mud, sand, or rock substrates, submerged aquatic vegetation, and emergent marsh, although soft bottoms are preferred. Adult specimens of C. maenas are euryhaline, meaning they can tolerate a wide range in salinity (from 4 to 52 ‰), and survive in temperatures of 0 to 30 °C (32 to 86 °F). The wide salinity range allows C. maenas to survive in the lower salinities found in estuaries, and the wide temperature range allows it to survive in extremely cold climates beneath the ice in winter. Early life stages are more constrained in their tolerances; for example, larvae survive from hatch to metamorphosis to megalopa at temperatures between 12 and 27 °C.

Carcinus maenas is fished on a small scale in the northeast Atlantic Ocean, with about 1200 tonnes being caught annually, mostly in France and the United Kingdom. In the northwest Atlantic, C. maenas was the subject of fishery in the 1960s, and again since 1996, with up to 86 tonnes being caught annually.