# Brittle Star (*Ophiothrix fragilis*)

> The common brittle star (Ophiothrix fragilis) forms dense carpets on northeast Atlantic gravel, arms raised to filter feed. Adults reach 15 cm arm span and are Least Concern.

- **Category:** Invertebrate
- **Conservation status (IUCN):** Least Concern
- **Range:** Northeast Atlantic rocky and gravel seabeds.
- **Canonical page:** https://globalanimalguide.org/animals/brittle-star/
- **Last reviewed:** 2026-07-16

## Scientific classification

- **Kingdom:** Animalia
- **Phylum:** Echinodermata
- **Class:** Ophiuroidea
- **Order:** Ophiurida
- **Family:** Ophiotrichidae
- **Genus:** Ophiothrix

## Facts at a glance

| Attribute | Value |
| --- | --- |
| Scientific name | Ophiothrix fragilis |
| Diet | Detritivore / filter feeder |
| Habitat | Rocky and gravel bottoms |
| Lifespan | 3–5 years |
| Weight | 0.01–0.02 kg |
| Top speed | up to 2 km/h |
| Conservation status | Least Concern (IUCN) |

## Arms that break to escape

Long flexible arms detach easily when grabbed, regenerating later. A central disc hides the mouth; tube feet lack suckers unlike true starfish.

## Filter feeding in aggregations

Arms are held vertical in current to trap plankton. Winter aggregations can cover thousands per square metre on gravel bottoms.

## Northeast Atlantic gravel beds

From Norway to the Mediterranean on rocky and gravel seabeds. Trawling disturbance can break arms but populations rebound by regeneration.

## Swarm engineer

Least Concern and often superabundant. Dense mats alter sediment chemistry and provide food for fish and crustaceans.

## Frequently asked questions

### Why are they called brittle stars?

Arms snap off easily under predator attack and regrow over time.

### How do brittle stars feed?

Many species filter plankton with raised arms; others scavenge detritus on the seabed.

### Are brittle stars the same as starfish?

They are related echinoderms in class Ophiuroidea with thinner, more flexible arms.

### Can brittle stars regrow arms?

Yes — lost arms regenerate if the central disc survives.

### Why do brittle stars form dense beds?

Current-fed gravel offers ideal filter-feeding conditions, triggering huge aggregations.

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Source: Global Animal Guide (https://globalanimalguide.org/animals/brittle-star/). Licensed CC BY-NC 4.0 — free for non-commercial reuse with attribution.