Common brittle star

Ophiothrix fragilis

The common brittle star is a small echinoderm with thin, flexible arms. It can form dense seabed colonies that strain food from passing water.

Key facts

Common brittle star (Ophiothrix fragilis) is a filter feeder animal classified as Invertebrate · Amphilepidida · Ophiotrichidae.
Primary habitats are coast · open ocean, with a range across Atlantic Ocean · Palearctic.
Activity is nocturnal, sociality is colony, and conservation status is LC (Least Concern).
The common brittle star is a small echinoderm with thin, flexible arms.
It occurs along Atlantic and Palearctic coasts and deeper bottoms.
Typical lifespan: 5–10 years

Habitat range map

Native rangeOccasional / Transient

Map: Ecoregions 2017 © RESOLVE (CC BY 4.0) · Natural Earth (PD)

It occurs along Atlantic and Palearctic coasts and deeper bottoms. Rocky reefs, shell gravel, and mixed sediment with many crevices provide shelter.

Arm span 8-15 cm; weight 2-20 g. Five long spiny arms extend from a small central disc. The arms break easily but can regenerate.

Nocturnal and colonial, it often hides the disc while extending arms into current. When disturbed it flicks the arms rapidly and retreats.

A filter-feeder, it catches plankton and organic particles with raised arms. It may also pick detritus and small fragments from the bottom.

Adults broadcast eggs and sperm into the sea, producing drifting larvae. Settled juveniles can build dense beds where conditions are favorable.

It is listed as Least Concern. In large aggregations it moves suspended particles into the benthic food web.