Sea hare
Akeroidea
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Sea hares (also called
sea slugs) are small marine
gastropod molluscs of the suborder
Anaspidea (P. Fisher, 1883) in the subclass
Orthogastropoda, class
Gastropoda, phylum
Mollusca. Their common name derives from the projections on their bodies which somewhat resemble
rabbit ears. Their scientific name (Anaspidea) is derived from the
Greek for "without a shield" and refers to the lack of the head shield which characterises other members of the Opisthobranchia.
Sea hares are large, bulky creatures, reaching a length of up to 75 cm and weight of up to 2 kg. They have soft bodies with an internal shell and are all
hermaphroditic, acting as male and female simultaneously, even during mating.
Sea hares are
herbivorous and are typically found on
seaweed in shallow water. When there is a shortage of food, they burrow themselves. They have an extremely good sense of smell. They follow even the faintest scent with the chemoreceptors on their tentacles.
They rely for protection on their coloration, which
camouflages them from predators. When disturbed, a sea hare can release ink from its ink glands, providing a potent deterrent to predators such as
sea anemones. This release acts as a smoke screen, while, at the same time, affecting the scent of their predators. The color of the ink is white or reddish, depending on the color of the pigments of the seaweed. Their skin contains a similar toxin that renders sea hares largely inedible for many predators.
Many anaspideans have only an thin, internal and much-reduced shell with a small mantle cavity; some have no shell at all. All species have a
radula and gizzard plates.
Aplysia californica is a typical example of a sea hare, and is noteworthy for its usefulness in studies of
neurobiology.
