Open brain coral

Lore & Background

Open brain corals can be solitary or colonial, rarely reaching over 20 cm in diameter. They exhibit a flabello-meandroid growth form with distinct valley regions separated by walls; in colonial forms, these valleys can contain multiple polyps. The valley complexity varies, from hourglass-shaped to highly lobed, and the corals typically have bilateral symmetry. During the day when the polyp is closed, the coral is covered by a fleshy mantle that extends beyond the skeleton but can retract when disturbed. Colonies can be blue, green, yellow, or brown, and are often vibrantly colored. Open brain corals are found throughout the Indo-Pacific, from the Red Sea to New Caledonia, up to a maximum depth of 40 meters. They are less common directly in coral reef communities and are more often found on sandy reef slopes, around continental islands, and lagoons. They can often be found near other free-living corals. Large colonies are uncommon and are typically only observed in marine protected areas. The open brain coral is known to host a species of gall crab, Lithoscaptus semperi. The IUCN lists the species as near threatened due to habitat loss and over-harvesting for the aquarium trade. The biggest exporter is Indonesia, which in 2005 exported over 60,000 open brain corals for aquarium use. Other threats include disease, acidification, and severe storms.

Reader's Guide

The open brain coral is a free-living species in the family Merulinidae, notable for its flabello-meandroid growth form with distinct valley regions separated by walls. It can be solitary or colonial, rarely exceeding 20 cm in diameter. During the day, a fleshy mantle covers the skeleton and can retract when disturbed. The coral is found throughout the Indo-Pacific, from the Red Sea to New Caledonia, at depths up to 40 meters. It is less common on coral reefs and more typical of sandy reef slopes, continental islands, and lagoons, often near other free-living corals. Large colonies are uncommon and mostly observed in marine protected areas. The species hosts a gall crab, Lithoscaptus semperi. The IUCN lists it as near threatened due to habitat loss and over-harvesting for the aquarium trade. Indonesia is the largest exporter; in 2005 it exported over 60,000 specimens for the aquarium trade. Additional threats include disease, acidification, and severe storms.

Did You Know?

• The open brain coral is the only species in the monotypic genus Trachyphyllia.
• It can be solitary or colonial, and rarely exceeds 20 cm in diameter.
• In 2005, Indonesia exported over 60,000 open brain corals for the aquarium trade.