Homarus gammarus , known as the European lobster or common lobster , is a species of clawed lobster from the eastern Atlantic Ocean , Mediterranean Sea and parts of the Black Sea . It is closely related to the American lobster , H. americanus . It may grow to a length of 60 cm ( 24 in ) and a mass of 6 kilograms ( 13 lb ) , and bears a conspicuous pair of claws . In life , the lobsters are blue , only becoming " lobster red " on cooking . Mating occurs in the summer , producing eggs which are carried by the females for up to a year before hatching into planktonic larvae . Homarus gammarus is a highly esteemed food , and is widely caught using lobster pots , mostly around the British Isles .