Black Brittle-star

Overview

The Black Brittle-star (Ophiocomina nigra) is a large, distinctive echinoderm often found in dense aggregations on the seafloor. It is widely distributed across the northeastern Atlantic, North Sea, and Mediterranean, where it plays a significant role in benthic ecosystems.

Appearance

This species is characterized by a round, flattened central disc that typically reaches up to 2.5–3 cm in diameter. It features five long, flexible arms that can grow to approximately five times the diameter of the disc. While the common name suggests a black coloration, individuals can also appear in various shades of brown, and pale or nearly white specimens are occasionally found. The upper surface of the disc is covered in fine granules, and each arm is lined with a prominent row of erect spines that resemble the teeth of a comb.

Distribution & habitat

Ophiocomina nigra inhabits a variety of hard and mixed substrates, including bedrock, boulders, and gravel. It is frequently found in moderately exposed coastal areas with sufficient water movement. While it can be found from the intertidal zone down to depths of 400 meters, it is most commonly encountered in shallower circalittoral waters. This species is known to form massive, dense beds that can contain millions of individuals, sometimes in association with other brittle-star species like Ophiothrix fragilis.