Also known as a true lobsternorthern lobster, or Maine lobster, these crustaceans can reach a body length of 25 inches, and a mass of over 44 pounds - making them not only the heaviest crustacean in the world, but also the heaviest of all living arthropod species.

Its closest relative is the European lobster Homarus gammarus, which can be distinguished by its coloration and the lack of spines on the underside of the rostrum.

American lobsters are usually bluish green to brown with red spines, but a number of color variations have been observed.