Sponge Brittle Star in Cozumel
Sponge Brittle Star (*Ophiothrix suensonii*) in Cozumel: how to identify it, where it lives, and why it sheds its arms.
Five very thin, spiky, banded arms radiating from a tiny central disc, wrapped around or draped over a sponge or sea rod. Arms are fringed with fine glassy spines.
Quick ID
| Scientific name | Ophiothrix suensonii |
|---|---|
| Group | Echinoderms — Urchins & Sea Stars |
| Typical size | Arm span 10–20 cm |
| Depth range | 5–30 m |
| When to see it | Year-round |
| Active | Night |
| Conservation status | Least Concern |
| Notes | Best seen on night dives |
Where You Will See It In Cozumel
On rope sponges and gorgonians at Santa Rosa, Palancar and Punta Tunich, most visible at night.
Reliable sites: Santa Rosa Wall, Palancar Caves, Punta Tunich.
Behaviour
Lives on a host sponge and filters particles from the water with its arms. Sheds arm segments when grabbed — the brittle in the name is literal, and it is a defence.
Commonly Confused With
- Basket star — Basket stars are much larger with intricately branched arms and unfurl into a mesh at night.
- Feather stars — Crinoids have feathery arms and grip with small claws.
Diving Etiquette And Safety
Do not touch. The arms break by design and a handled animal loses limbs.
Part of the Cozumel marine life guide · see Cozumel dive sites · plan your Cozumel dive trip
Photo: Jay Brasher, CC BY 4.0, via Wikimedia Commons.
