Thuridille De Hope

Overview

Thuridilla hopei is a striking sacoglossan sea slug primarily found in the Mediterranean Sea, with some populations recorded in the nearby Atlantic, such as the Azores. This shell-less gastropod is well-known for its vibrant coloration and distinctively patterned body, making it a recognizable species for divers and marine enthusiasts.

Appearance

This sea slug typically measures between 10 and 25 mm in length and features a slender, smooth body. Its most prominent features are the large, sail-like parapodia—lateral extensions that fold over the back to form an elongated sheath from which the head emerges. The body is generally blue to violet, though it can appear greenish, gray, or even black. The parapodia are adorned with three distinct colored bands, often including a bright yellow or orange outer border. The head bears two robust, rolled rhinophores and a characteristic white 'V'-shaped marking located between them, accompanied by small black eye spots at the base.

Distribution & habitat

While endemic to the Mediterranean, the species has also been documented in the Azores. It prefers well-lit, rocky environments where algae thrive, often inhabiting shallow coastal waters from the surface down to depths of approximately 40 meters. It is frequently observed in close proximity to green or brown algae.

Feeding

Thuridilla hopei is a herbivore that feeds on small green algae. It utilizes a specialized radula to puncture the cell walls of the algae to extract nutrients.