About Aplysia depilans Gmelin, 1791
This species, Aplysia depilans Gmelin, 1791, is a type of sea hare. Mature individuals can reach up to 40 centimeters in length and weigh up to 380 grams. Their skin ranges from dark brown to reddish brown, marked with white to light brown blotches. The species has an internal yellow shell that measures approximately 1.5 centimeters long; this shell is thinner, flatter, and more poorly calcified than the shells of other sea hares. The shell is oblong, ovate, smooth, and shining, and features faint light radial grooves. The interior of the shell is testaceous, meaning it has a shelly texture. The apex of the shell is incurved, reflected, and slightly calloused. Its upper margin is excavated, reflected near the apex, and wedge-shaped (cuneate) at its tip. The outer lip of the shell is slightly convex, the dorsal margin is convex, and the lower margin is only barely excavated. Aplysia depilans is distributed in the eastern Atlantic Ocean and the Mediterranean Sea. It is most commonly found in shallow water between 1.5 and 10 meters deep. The species avoids the intertidal zone, as it cannot absorb atmospheric oxygen and dies relatively quickly after becoming stranded. Occasionally, individual sea hares become trapped in tide pools during low tide. Adult Aplysia depilans feed primarily on algae from the genus Ulva, especially the sea lettuce species Ulva lactuca. During their planktonic life stage, individuals feed on single-celled phytoplankton.
