Platygyra lamellina
A near-threatened brain coral of Indo-Pacific reefs.
Platygyra lamellina, called the hard brain coral, is a colonial stony coral belonging to the Merulinidae family. It is found on shallow-water reefs throughout the Indo-Pacific region. The IUCN lists its conservation status as near threatened.
Colonies of this species typically grow as massive, rounded mounds, sometimes with lumpy swellings, though flat plate-like forms also occur. Its corallites are long, narrow, and winding, with thick walls that can be up to one and a half times the width of the valleys between them. The septa are neatly arranged, slightly protruding, rounded, and even, crossing over the valley walls. The coral is usually some shade of brown, with valley bottoms occasionally appearing greenish or grey. It can be told apart from the similar *Platygyra daedalea* by its thicker corallite walls and more rounded septa.
*P. lamellina* has a broad distribution across the Indo-Pacific but is generally uncommon. Its range stretches from Madagascar, the eastern coast of Africa, and the Red Sea to Australia, Indonesia, Japan, and the East China Sea. It lives in various reef habitats, especially on back reef slopes, but also on fore reefs and in lagoons.
This species is a simultaneous hermaphrodite. Spawning happens at night during summer, timed by the moon’s phase; in the Red Sea, this occurs over three to five days around the new moon in July and again in August. The corals release buoyant clusters of eggs and sperm that rise to the surface. Fertilization takes place at least twenty minutes later, after the eggs and sperm have dispersed. Neither the eggs nor the planula larvae—which develop about two days later—contain zooxanthellae. The planulae settle on the seabed roughly two months later and metamorphose into polyps. Their slow development is thought to result from the lack of zooxanthellae, which are acquired at the primary polyp stage in this species.
Quick Facts
- Taxon
- Platygyra lamellina
Facts from the source article.
Lore & Background
Colonies of Platygyra lamellina usually form massive rounded mounds, sometimes with nodular swellings, but may also form flat plates. The corallites are long, narrow and meandering, with thick walls up to one and a half times the thickness of the valleys between them. The septa protrude slightly and are rounded and even, very neatly arranged, crossing the valley walls. This coral is usually some shade of brown, with valley bottoms sometimes greenish or grey. It can be distinguished from the otherwise similar Platygyra daedalea by the thickness of the corallite walls and the more rounded septa.
P. lamellina has a widespread distribution in the Indo-Pacific region but is generally uncommon. Its range extends from Madagascar, the east coast of Africa and the Red Sea, to Australia, Indonesia, Japan and the East China Sea. It is present as part of the reef community in various habitats, particularly on back reef slopes, but also on fore reefs and in lagoons.
Spawning occurs at night during the summer on a date determined by the phase of the moon; in the Red Sea, this is the three- to five-day period around the new moon in July and the similar period in August. Clusters of eggs and sperm are released, buoyant, and rise to the surface. Fertilisation takes place at least twenty minutes later, after dispersal. Neither the eggs nor the planula larvae contain zooxanthellae. The planula larvae settle on the seabed about two months later and undergo metamorphosis into polyps. The slow development of the larvae is believed to be due to the absence of zooxanthellae, which are acquired at the primary polyp stage.
Reader's Guide
Platygyra lamellina is notable as a near-threatened species of brain coral within the family Merulinidae, reflecting its vulnerability in shallow Indo-Pacific reef ecosystems. Its description highlights distinctive morphological features—thick corallite walls and rounded septa—that allow differentiation from the similar Platygyra daedalea. The species is widespread but generally uncommon, occurring across a broad geographic range from East Africa to Japan. Its reproductive biology is documented in detail: as a simultaneous hermaphrodite, it spawns at night during summer, timed to lunar phases, with buoyant egg-sperm clusters that fertilize after dispersal. The absence of zooxanthellae in eggs and larvae is linked to slow larval development, with symbionts acquired only at the primary polyp stage. This life-history trait may influence its recruitment and distribution. The IUCN near-threatened status underscores the need for monitoring, though the article provides no specific threats or population trends. The species' presence in varied reef habitats—back reef slopes, fore reefs, and lagoons—indicates ecological flexibility, yet its uncommonness suggests sensitivity to environmental changes.
Did You Know?
- Platygyra lamellina is a simultaneous hermaphrodite.
- In the Red Sea, spawning occurs around the new moon in July and August.
More in Brain and Merulinid Corals 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced