About Aplysia fasciata Poiret, 1789
Aplysia fasciata can reach a maximum length of 40 cm. Its body is most often black or very dark brown; the parapodia, foot, and tentacles sometimes have a thin red border. Many individuals have mottled spots across their body, which gives the species its common name "mottled sea hare". Like most sea slugs, this species has two oral tentacles and two smaller rhinophores located on the front of its neck. The eyes sit in front of the rhinophores. A small, rounded "tail" is present on the animal's rear end. A mantle covers the gills and internal organs. A thin, delicate inner shell lies inside the mantle. This shell is concave, amber in color, with a slightly hooked apex, and it is also rather solid, broad, and obliquely subquadrate. The shell is tumid (swollen), arched, and pale brown, with a testaceous (shelly) interior and light concentric striations. The apex is elevated, incurved, and calloused. The upper margin of the shell is short and slightly excavated; the outer lip is convex and extended forward. The lower margin is oblique and widely excavated, while the dorsal margin is thickened and rather calloused. An ink gland is also located inside the mantle. This sea hare is found in the Western Atlantic from New Jersey to Brazil, and in the Eastern Atlantic including the Mediterranean Sea, the West African coast, and the Atlantic coast of France. It is a rare visitor to waters off the southern British Isles. The related species Aplysia punctata is a regular resident along most British coasts and in the northeast Atlantic. Some researchers regard Aplysia brasiliana, a species found along the Atlantic coast of the Americas, as a synonym of Aplysia fasciata, representing only a regional difference in color pattern.
