SpinyheadPlay freeBrain coral Scleractinia (Faviidae/Mussidae)
Brain corals are massive reef-building stony corals whose surface is covered in winding valleys and ridges that look like the folds of a brain. Each colony is made up of many genetically identical polyps. In the meandering valleys the polyps share continuous rows of mouths and tentacles. Colonies grow slowly into domes or heads, and large ones can be centuries old. They are important contributors to the reef framework on Caribbean reefs. The name covers several species, mainly the symmetrical brain coral (Pseudodiploria strigosa), the grooved brain coral (Diploria labyrinthiformis) and the boulder brain coral (Colpophyllia natans).
How to recognize it
- rounded dome or boulder shape
- winding valleys and ridges
- brain-like maze pattern
- ridges often with a central groove
- tan, brown, yellow-brown or greenish color
- hard, stony, smooth-looking surface
- tentacles extended at night
| Size | Colonies are typically tens of centimeters to about 1 m across. The largest, such as boulder and symmetrical brain corals, can reach roughly 1.5 to 2 m. |
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| Range | Tropical western Atlantic: Florida, the Bahamas, the Gulf of Mexico, the Caribbean Sea and Bermuda, south to Brazil depending on species. |
| Habitat | Common on forereefs, reef crests, patch reefs and back reefs, from the shallows to roughly 40 m or more depending on species. Some species do well in shallow, wave-exposed water, while others are more common on deeper slopes. |
| Diet | Brain corals get much of their energy from symbiotic algae (zooxanthellae) living in their tissue, which provide sugars through photosynthesis. They also feed at night, extending tentacles to catch zooplankton and other small particles, and they can take up dissolved organic matter. Some species have longer sweeper tentacles used against neighboring corals. |
| Conservation | Status varies by species. Some brain corals have been assessed by the IUCN as threatened or near threatened, while others are of lesser concern, so check the individual species. Major threats include stony coral tissue loss disease, which strongly affects many brain corals, along with coral bleaching from marine heatwaves, other diseases, poor water quality, physical damage and ocean acidification. |
Life and behavior
Each colony grows by adding new polyps and by extending its limestone skeleton, usually slowly, only a few millimeters to about a centimeter per year. Many brain corals are hermaphroditic broadcast spawners. They release eggs and sperm packets into the water on a few nights after the full moon, typically in late summer, and the fertilized eggs develop into drifting larvae before settling on hard surfaces. Colonies can also spread by fragmentation after storms or damage. Corals compete for space with neighbors using sweeper tentacles and digestive filaments. Individual colonies can live for many decades to centuries.
Its family: Brain and favioid reef corals (Faviidae / Mussidae)
These are large-polyped or closely packed stony corals, many of them massive and reef-building, with calcium carbonate skeletons and symbiotic algae. Colony shapes include domes, plates and boulders, with either separate cups or meandering valleys. Classification has been revised in recent years, so some brain corals formerly placed in Faviidae are now in other families such as Mussidae or Diploriidae, depending on the source.
Similar species
- Knobby brain coral Pseudodiploria clivosa Has broader valleys and wider, more irregular ridges, and often grows as a knobby, lumpy or encrusting mass in shallow, wave-swept water.
- Grooved brain coral Diploria labyrinthiformis Has wider valleys with a distinct deep groove along the top of each ridge, and a more yellow-green or tan color.
- Boulder brain coral Colpophyllia natans Has much broader, deeper valleys, often with contrasting colors of green, brown or gray, and the colonies are larger, rounder boulders.
- Maze coral Meandrina meandrites Forms shorter, more sinuous valleys with tall ridges, giving a more sculpted look. It usually has a smaller, more rounded colony with a clearly different valley pattern.