Mottled Sea Hare – Aplysia fasciata

The Mottled Sea Hare, also known as the Sooty Sea Hare or the Black Sea Hare, is a species in the family of the Aplysiidae and thus belongs to the class of the Gastropoda.

Mottled Sea Hare - Aplysia fasciata Martin Gastropoda diving canary islands atlantic ocean canaries species
Mottled Sea Hare – Aplysia fasciata
Copyright: Martin Majewski


When it is rolled up, the Mottled Sea Hare has a long-stretched body in the form of an American football. When its wings are spread out, it is almost circular. Its colouration varies from dark brown to black with lighter spots. The edge of his wings is red. Aplysia fasciata reaches a maximum size of 40cm in length and a maximum weight of one kilogram.

Habitat and Distribution

The Mottled Sea Hare lives on rocky ground, preferring regions with algae growth. When diving in the Canaries you can observe it from time to time. It is also spread from the Atlantic coast of France, to Spain, Portugal all the way to West Africa. It is also found in the Mediterranean Sea and rarely on the coasts of Great Britain.


The life cycle of Aplysia fasciata takes about one year. It starts in February and stops in September. The beginning of the seaweed growth in the spring introduces the metamorphosis of the plankton-like larva to the young sea hare. As an adult animal they mate several times and lay eggs until they die in September. As an adult animal they spend only 4 months of their lives.

A nest of the Mottled Sea Hare has about 26 million eggs. These hatch after 15 days.

In the mating season, small groups can come together and mate with each other. Aplysia fasciata is a hermaphrodite, the animal with the larger sexual drive takes the male role.

They are nocturnal and have an economical metabolism, which means they have a lot of time to reproduce and need little time to eat. Their diet consists of brown, red and green algae, preferring the seaweed Ulva lactuca.

The Mottled Sea Hare can defend with a cloud of purple ink and they are known to be good swimmers.

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