Seven Armed Sea Star

Overview

The Seven-armed Sea Star (Luidia ciliaris) is a large, distinctive echinoderm easily recognized by its seven long, slender arms radiating from a small central disk. It is a predatory species commonly found across the temperate eastern Atlantic and the Mediterranean Sea, where it inhabits soft-sediment seafloors.

Distribution & habitat

This species is distributed from the Faroe Islands and Norway in the north, down to the coasts of West Africa and the Cape Verde islands, and throughout the Mediterranean. It favors sandy, muddy, or gravelly bottoms, often partially burying itself in the substrate to remain hidden or to ambush prey. While it can be found from the lower shore, it is most frequently observed at depths between 20 and 400 meters.

Appearance

Typically reaching 40 to 60 cm in diameter, Luidia ciliaris displays a coloration ranging from orange-brown to red, with a lighter underside. Its seven arms are of consistent width, tapering only near the tips, and are bordered by a conspicuous fringe of stiff, white spines. The upper surface is covered in small, pillar-like structures called paxillae. Its long tube feet lack suction pads, which is a key identifying feature.

Biology & behavior

Known for its relatively high metabolic rate and rapid movement, this sea star is a capable hunter. It often moves across the seabed with its central disk raised, a posture that may serve as a warning to other animals. It is a fragile species and can easily lose arms if attacked, though it possesses a strong capacity for regeneration, often resulting in individuals with arms of varying lengths. It is generally solitary and prefers darker, deeper environments.