Carcinus maenas crabs (Linnaeus, 1758) are known as the European green shore crabs (Decapoda, Heterotremata. Cancroidea). They are fast and voracious predators native to the Atlantic coasts of Europe and Africa. Since the 1800's they have been reported to invade American waters. Their speed dexterity, and ability to learn while foraging has made them a threat to west coast native crabs (namely Cancer magister) and to the shellfish industry.

This crabs inhabit coastal water from the intertidal to 60m depths. They can tolerate wide changes in salinity (4-54 ppt) and temperatures (0-33ºC). They feed on bivalve mollusks, small crustaceans, and polychaetes.

They are green to brown in color and have five spines on the frontal carapace distal to the eyes. They reach sizes of 10 cm long and are at home walking on land as well as underwater.

This species has been used as a system in the study of the neuroethology of walking for decades. In our lab we are currently studying the process of neural augmentation and facilitation using these crabs. We further employ them in projects ranging from comparative studies on skeletal and neural anatomy of the walking machinery to recordings of kinematic and muscular activity of freely walking animals.

Below is a tree of proposed crustacean relationships based on multiple approaches (Martin and Davis, 2001). We show the species we study plus the other brachyuran shown to walk forwards (the soldier crab, Mictyris).