Grooved Brain Coral (Diploria labyrinthiformis)

Status: needs expert review. The conservation category for this species is contested (see below); a science reviewer should confirm the current IUCN assessment before approval. Grooved brain coral (Diploria labyrinthiformis) is a slow-growing, massive (boulder-forming) reef coral of the Caribbean, the Bahamas, southern Florida, and Bermuda.

At a glance

Field	Value	Source
Scientific name	Diploria labyrinthiformis	WoRMS / authority
Guild	reefs (reef-building coral)	—
IUCN status	Listed Least Concern (assessment 2008); contested — see Conservation status	IUCN Red List
Population trend	Decreasing	IUCN / literature
International trade	CITES Appendix II (all stony corals, Scleractinia)	CITES
Range	Caribbean, Bahamas, southern Florida, Bermuda	IUCN Red List

Identification

A massive, rounded ("boulder" or "brain") coral whose surface is covered in deep, meandering grooves and ridges that resemble the folds of a brain — the feature that gives the genus its name. Unlike branching corals it grows slowly and forms dome-shaped colonies.

Ecology and role

Grooved brain coral is a colonial animal living in symbiosis with photosynthetic algae (zooxanthellae); heat stress can break that symbiosis and cause bleaching (NOAA). As a massive, long-lived boulder coral it contributes durable framework to the reef structure — the slow-built, wave-resistant base on which Caribbean reefs persist — a habitat-forming, foundation role distinct from fast-growing branching corals. Detailed claims should be cited to published research and confirmed in review.

Conservation status and threats

The conservation category for this species is contested. The IUCN Red List entry was assessed as Least Concern (2008), largely reflecting a wide Caribbean distribution at the time of assessment. However, the species is highly susceptible to stony coral tissue loss disease (SCTLD) — an emerging, fast-spreading Caribbean outbreak documented from 2014 onward — and to warming-driven bleaching, and more recent literature and survey data report steep local declines that point toward a more threatened status pending reassessment (NOAA Coral Disease & Health Consortium; literature). This page represents the disagreement rather than resolving it: a science reviewer should confirm whether the current published IUCN category has been updated. More broadly, the IUCN reported in 2024 that over 40% of reef-building coral species face extinction (IUCN). The dominant ongoing stressors are heat stress and disease; the Coral Reef Watch dataset is the early-warning signal for the thermal-stress component.

How to observe responsibly

This page does not provide approach guidance. Coral is fragile and easily killed by contact. Never touch, stand on, or kick coral; maintain neutral buoyancy; never collect coral (and note CITES restrictions). Follow the reviewed observation guide and local marine-park rules. Reef-restoration sites are sensitive — keep to regional granularity (ETHICS.md).

How you can help

• Log reef condition and coral sightings via recognized programs such as Reef Check or iNaturalist.
• Support coral-restoration and disease-response programs run by credible organizations.
• Reduce heat-stress drivers: the deepest help for coral is climate action.