About Ascidiella aspersa (Müller, 1776)
Ascidiella aspersa, commonly called the European sea squirt, is a species of solitary sea squirt. It is native to the northeastern Atlantic, ranging from the Mediterranean Sea to Norway. This species has oval bodies that reach 50 to 130 mm (2.0 to 5.1 in) in length. Its branchial, or oral, siphons are conical, positioned at the top of the body, and have six to eight lobes. The atrial siphons are located on the upper third of the side of the body and have six lobes. The entire body is covered by a firm, transparent test that ranges in color from greyish to brown. This test often catches detritus, which stays loosely attached to the animal. When the animal is expanded, up to 40 tentacles can be seen on the inner surface of the branchial wall. The rims of both the branchial and atrial siphon openings have lighter colored ridges, and these rims may sometimes be frilled. A. aspersa attaches to substrates using the left side of its body. It can be found in dense groups of unfused individuals growing on hard surfaces such as rocks, at depths of up to 90 m (300 ft). Ascidiella aspersa closely resembles Ciona intestinalis, but can be told apart by its lack of yellow markings around its siphons.
