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
Sponge Brittle Star works the 16 to 98 foot band. On this island that means the sheltered west-coast reefs, and the shallow east-side entries when the sea is flat — these are the sites where the depth and the habitat line up for it.
Without a boat. It is worth looking for at El Mirador, El Presidente and Money Bar — all shore entries, so you dive them on your own schedule.
On an ordinary beginner boat dive. It should be within reach at Palancar Gardens, Paradise, Punta Dalila, San Clemente and Yellow House. No advanced certification needed.
Deeper, and on the walls. It is also plausible on Punta Sur, Punta Tunich, San Francisco Wall and San Juan.
Conditions change the odds more than the site does — the current, the time of day and how much the group has already stirred up the sand. Ask your guide what they have been seeing that week.
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.
Sponge Brittle Star Photos
Frequently Asked Questions
Why are they called brittle stars?
Where do you find sponge brittle stars?
What do they eat?
How do you tell one from a basket star?
Diving Cozumel soon?
Tell us your dates — we'll send options and connect you with the right dive shop.