Common brittlestar  (Ophiothrix fragilis)

The common brittlestar forms dense aggregations offshore, with as many as 2000 individuals recorded per square meter (2). When it occurs in the intertidal zone, it is more typically found as single individuals in crevices, under stones and amongst seaweed (4). It feeds by raising the arms above the substrate, and extending the tube-feet, which remove particles from the water (3). It then passes food along the arms to the mouth (3). It is also known to scavenge on decaying matter (3).

Many species predate on this brittlestar. It tends to avoid predation by moving away from any disturbance (2). Cryptic colouration and a tendency to hide in crevices may also help it to reduce the risk of predation (2). Study of bands in the skeletons of this species has suggested that it may be fairly long-lived, with the largest specimens estimated to be around 10 years old (2). The breeding season is thought to extend from May to January, although most reproductive activity seems to occur in summer and autumn (2). Each individual is believed to spawn just once each breeding season (2). A week after spawning, the planktonic larvae appear in the water column (2). They metamorphose into young brittlestars whilst drifting in the plankton, before settling after around 26 days (2).