Homarus americanus; Print; The American lobster (Homarus americanus) is a species of lobster found on the Atlantic coast of North America; chiefly from Labrador to New Jersey. It is also known as Atlantic lobster; Canadian lobster; true lobster; northern lobster; Canadian Reds; or Maine lobster. It can reach a body length of 64 cm (25 in); and a mass of over 20 kilograms (44 lb); making it 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 several color variations have been observed.