Figure 1.

Six ecotypes of Littorina saxatilis illustrating the extensive variation in shell size and form that is present within this species. All the individuals are adults of representative size and shape. Upper row from left to right: ‘neglecta’—an ecotype living in the empty shells of dead barnacles in the UK and France, ‘S’—a crab-resistant ecotype found on boulder shores along the Swedish west coast, ‘E’—a wave-resistant ecotype confined to granite cliffs on the Swedish west coast. Lower row from left to right: ‘groenlandica’—a large ecotype found in subarctic areas along with ecotypes of smaller size, ‘SU’—a wave-resistant Spanish ecotype and ‘RB’—a crab-resistant Spanish ecotype.