How fast does brain coral grow?

Roughly half a centimetre to a centimetre a year — a large colony is centuries old.

How do you tell brain corals apart?

The grooved brain coral has a groove along the top of each ridge; the symmetrical brain coral does not.

When do the polyps come out?

At night, which is why a night dive on a familiar reef looks completely different.

All coral inside the Cozumel Reefs National Park is protected from damage and collection.

Brain Coral in Cozumel

Symmetrical Brain Coral (*Pseudodiploria strigosa*) in Cozumel: how to identify it, how slowly it grows, and what it is confused with.

A rounded boulder covered in a maze of interconnected valleys and ridges, tan to yellow-green. The valleys are continuous, not separate pits.

Quick ID

Scientific name	Pseudodiploria strigosa
Group	Hard Corals
Typical size	Colonies to 2 m across
Depth range	2–30 m
When to see it	Year-round
Active	Polyps feed at night
Conservation status	Least Concern
Notes	—

Where You Will See It In Cozumel

Reef structure throughout Cozumel — Tormentos, Yucab and Paso del Cedral are covered in them.

Reliable sites: Tormentos, Yucab, Paso del Cedral.

Behaviour

A slow reef-building coral, growing roughly half a centimetre to a centimetre a year. A brain coral the size of a car is centuries old. Polyps extend to feed after dark.

Commonly Confused With

Grooved brain coral — Grooved brain coral has a distinct groove running along the top of each ridge.
Star coral — Star coral has separate raised polyp cups rather than continuous valleys.

Diving Etiquette And Safety

Slow growth means damage is effectively permanent. Do not touch, kneel on or steady yourself against coral.

Part of the Cozumel marine life guide · see Cozumel dive sites · plan your Cozumel dive trip

Photo: Emma Hickerson, NOAA Flower Garden Banks National Marine Sanctuary, Public domain, via Wikimedia Commons.