The origin of the common name for the reef-forming coral, Diploria labyrinthiformis, "brain coral", is readily apparent: this species forms large clumps, 6 to 8 feet (2 to 2.5 meters) in diameter, with a deeply convoluted surface reminiscent of a human brain. It is brownish yellow in life (Voss 1980). This "brain" is actually a colony of tiny cnidarian polyps (sea anemone-like animals) that secrete a hard calcareous skeleton. The polyps feed by catching food with their tentacles, as well as obtaining nutrients from symbiotic photosynthesizing dinoflagellate "algae".
|Author||Skeleton?||Mineral or Organic?||Mineral||Percent Magnesium|
|Cairns, den Hartog, and Arneson, 1986||YES||MINERAL||ARAGONITE|
|Cairns, Hoeksema, and van der Land, 1999||YES||MINERAL||ARAGONITE|
|Barrios-Su?z et al., 2002||YES||MINERAL||ARAGONITE|
Grooved brain coral, Diploria labyrinthiformis, grows in the Caribbean, Bahamas, southern Florida, and Bermuda. This species tends to grow on less solid and loose substrates of the ocean floor.
Biogeographic Regions: atlantic ocean (Native )
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Widespread distribution in the tropical western Atlantic, including the Gulf of Mexico, southern Florida, Bahamas, NW Caribbean, Puerto Rico, lesser Antilles and Bermuda.
The genus Diploria is a conspicuous, common, and abundant reef-building group throughout the wider Caribbean. It is endemic to (i.e., found only in) the Atlantic-Caribbean (Weil and Vargas 2010).
"It is found in the Caribbean, the Bahamas, southern Florida, and Bermuda" (Rossi -Snook, Wood, and Zeeh).
Diploria labyrinthiformis has very distinct valleys that contain polyps, and deeper grooves beneath the ridges. The valleys are 5-10 mm wide, up to 6 mm deep and u-shaped in a cross section. The ridges are wider than valleys, up to 15 mm, and have a concave profile with edges 2-4 mm higher than the rest of the ridge. Right angles of the plates, or septa, make it look like there are double combs in the valleys. Crests, or costae, of the septa form across the valley walls. Grooved brain coral tends to grow to longer lengths when inhabiting shallow waters. Colonies of D. labyrinthiformis can be one to two meters in diameter. Grooved brain coral can be a variety of colors including tans, yellows, and grays.
Range length: 2 (high) m.
Other Physical Features: ectothermic ; heterothermic ; radial symmetry
Grooved brain coral is in the order Scleractinia, stony corals. The optimum temperature for adult Scleractinia coral is between 25 and 29 degrees Celcius; the absolute minimal temperature is 18 degrees Celcius. Because it has a single-celled symbiotic algae within its cells, grooved brain coral needs to be at depths where light can penetrate the water. As a result, this species has a depth limit of approximately 50 meters. Diploria labyrinthiformis grows throughout the year around Bermuda and in other areas off the Carribean. This coral can live in high areas of sediments. Members of the genus Diploria are found in high abundance on Bermuda's reefs when compared to other corals. This high abundance is due to the fact that genus Diploria has lower juvenile mortality rates than other coral groups.
Range depth: 50 (high) m.
Habitat Regions: tropical ; saltwater or marine
Aquatic Biomes: reef
Habitat and Ecology
Habitat Type: Marine
Comments: Overall depth range cited from 0-40 m, but typically occurs shallower from 3-10 m on spur and groove reef and fringing reefs.
Water temperature and chemistry ranges based on 1068 samples.
Depth range (m): 0 - 81
Temperature range (°C): 25.995 - 28.067
Nitrate (umol/L): 0.115 - 3.505
Salinity (PPS): 35.091 - 36.613
Oxygen (ml/l): 4.285 - 4.746
Phosphate (umol/l): 0.020 - 0.239
Silicate (umol/l): 0.805 - 5.080
Depth range (m): 0 - 81
Temperature range (°C): 25.995 - 28.067
Nitrate (umol/L): 0.115 - 3.505
Salinity (PPS): 35.091 - 36.613
Oxygen (ml/l): 4.285 - 4.746
Phosphate (umol/l): 0.020 - 0.239
Silicate (umol/l): 0.805 - 5.080
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
D. labyrinthiformis (Linnaeus 1758) form crusts, plates, and sub-massive and massive boulders along a wide depth distribution (0–35 m) and is often abundant (Weil and Vargas 2010).
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Diploria labyrinthiformis depends primarily on suspension feeding of small marine invertebrates. This coral also has zooxanthellate algae. The symbiotic algae photosynthesize and supply the coral with nutrients and energy for calcification and growth.
Animal Foods: aquatic or marine worms; aquatic crustaceans; other marine invertebrates; zooplankton
Other Foods: microbes
Primary Diet: carnivore (Eats other marine invertebrates)
D. labyrinthiformis is in a sedimentary environment so because it can’t move around for food it has to depend on suspension to get nourishment. They prey on zooplankton and bacteria, by using their tentacles and extruded mesenterial filaments. They have nematocysts on their polyps, these nematocysts are triggered to capture and immobilize their prey. Also, mucus and cilia help in capturing and bringing food particles to the mouth (Rossi-Snook, Wood, and Zeeh). Furthermore, it also gets nourishment from symbiotic dinoflagellate algae and zooxanthellae, which is located in its polyps’ endodermal tissue layer (Rossi-Snook, Wood, and Zeeh).
Giant brain coral serves as homes for other organisms. Grazing by Diadema antillarum, the long-spined urchin, may benefit D. labyrinthiformis by reducing macroalgal growths. Zooxanthellate algae live within the cells of D. labyrinthiformis. The single-celled algae receives protection and feeds on coral waste, while the coral receives nutrients and energy from the algae.
Ecosystem Impact: creates habitat
- zooxanthellate algae
Common coral predators include gastropods, polychaetes, echinoids, asteroids, pycnogonids, and fishes, such as parrotfish.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 81 to >300
Comments: Information is needed on the number of occurrences in the tropical western Atlantic.
2500 - 10,000 individuals
Comments: Occurs on most classes of marine hardbottom communities, including low-relief hardbottom communities, patch reefs, fringing reefs, spur and groove reefs, transitional reefs and deeper intermediate reefs.
A84PET01FCUS: disease of unknown etiology. A89GOE01FCUS, A84LAS02FCUS, A90GHI01FCUS, A91WIL01FCUS: susceptible to bleaching (loss of zooxanthellae) due to adverse environmental conditions. A77DOD01FCUS: more resistant to sedimentation than D. strigosa. A81ANT02FCUS, A75GAR01FCUS: seldom inflicted with black band disease. A92WIT01FCUS: no recruitment on eutrophicated reefs. A92COL01FCUS: salinity tolerance to 55 ppt for 12 h. A85HUB01FCUS: growth rate at .33 cm/yr. A15VAU01FCUS: growth rate measured at 6.4-9.2 mm/yr increase in diameter and 4.9-7.5 mm/yr increase in height.
Life History and Behavior
There has been no research conducted on the communication and perception in D. labyrinthiformis. Many corals capture food with expanded tentacles suggesting a tactile response to the environment.
Perception Channels: tactile ; chemical
Grooved brain coral has a broadcaster mode of development. Diploria labyrinthiformis is fertilized internally and then releases eggs into the ocean. The eggs hatch into swimming planktonic planulae larvae, which settle on an appropriate substrate, where asexual reproduction begins. Secondary polyps are formed, which develop to adult polyps. This species can grow at a rate of 3.5 millimeters per year.
Development - Life Cycle: metamorphosis
The lifespan of D. labyrinthiformis is unknown. However, members of the genus Diploria are found in high abundance on Bermuda's reefs when compared to other corals. This high abundance is due to the fact that genus Diploria has lower juvenile mortality rates than other coral groups.
Grooved brain coral is hermaphroditic, with an annual gametogenic cycle with a 10-11 month period for gonad (sex organ) development. The typical spawning season of grooved brain coral is from late May to late June. Spawning likely begins for this species as a result of environmental cues such as high air temperature, low number of solar hours per month, low wind velocity, and initiation of the rainy season.
Grooved brain coral has an average of four mature eggs and six spermatic cysts per fertile mesentery. Eggs and spermatic cysts are located towards the aboral (opposite the mouth) part of the mesentery.
Breeding season: The breeding season is from late May to late June.
Key Reproductive Features: seasonal breeding ; sexual ; asexual ; fertilization (Internal ); oviparous
There has been no known parental care for D. labyrinthiformis. Eggs are released after they are fertilized.
Parental Investment: no parental involvement; pre-fertilization (Protecting: Female)
A83FAD00FCUS: hermaphroditic within polyps with septae normally male or female. Suggested sequential hermaphrodite.
Alvarado et al. (2004) studied the sexual reproduction of Diploria labyrinthiformis in Colombia and found that it is hermaphroditic (i.e., a single individual produces both eggs and sperm) and releases its gametes (eggs and sperm) in the spring, in contrast to the summer spawning of the other two Diploria species, D. strigosa and D. clivosa. Weil and Vargas (2010) studied the reproductive biology of all three species in Puerto Rico. primatily at the San Cristobal reef complex, where all three species had abundant large colonies. All three species were found to be simultaneous hermaphrodites (i.e., an individual produces both male and female gametes at the same time). Diploria strigosa and D. clivosa released gametes during August and/or September, but D. labyrinthiformis released its gametes in April and/or May (consistent with the findings of Alvarado et al. from Colombia). Of the three species, D. labyrinthiformis had the highest fecundity (an average of 36.5 eggs/polyp versus 27.2 for D. strigosa and 20.2 for D. clivosa). All three of these species are broadcast spawners, releasing their gametes into the water and providing no parental care (in some other coral species, known as brooders, fertilization and early development of larvae are internal, with larvae eventually released rather than gametes). Synchronized release of gametes (sperm and eggs) appears to be linked to lunar cycles, as well as other environmental cues.
- It forms large, rounded, often almost hemispherical colonies.
- Its skeleton (corallum) consists of numerous, elaborately intergrown, meandering, valley-like structures (meandroid corallites) which often branch.
Each valley is inhabited by a single long polyp with many mouths which are arranged serially or in a row along the valley, and all surrounded by a single shared set of tentacles. The valleys are:
- 5-10mm wide
- up to 6 mm deep
- U-shaped in cross section
Ridges are usually as wide or wider than the valleys - up to 15mm wide. The profile across the top of the ridges is U-shaped (concave), with edges 2-4mm higher than the rest of the ridge.
Coralla consist of two levels of coloniality (cf. modularity) as colonies grow by:
- increasing valley length, which is associated with the addition of new mouths at the ends of the valleys
- forming whole new valleys
In Diploria labyrinthiformis, numerous plates (septa) are aligned more or less at right angles to the valley walls, with 12-24 per cm of valley length. These give a double comb-like appearance to the valleys.The septa form crests (costae) across the walls. A single septum is continuous and integral with its respective costa. The complete structure is a costoseptum.
Appearance and pattern of costosepta
Costae slope down and across the coenosteal ridges that separate the valleys. Costae on the paired walls of the coenosteal ridges do not quite meet each other. Septa also slope steeply down into the central axis (fossa) of the valleys, but close to the fossa they are usually inflected into a less steep lobe-like segment (paliform lobe) before descending again to the fossa.Septa occur in 2-3 size orders, with respect to:
- how far they extend towards the fossa
- how high their costae are
- small irregular plates
- twisted elements running along the valley axis
Micro-morphology of costosepta
Costosepta are mostly imperforate except towards the fossa.They bear regular strong blunt teeth along all of their edges. These project more or less upward from the edges except close to the fossa where they project at various angles and contribute to the axial structure. Costoseptal faces bear small, fine spines or granules aligned in rows perpendicular to costoseptal margins. Rows may merge into fine ridges.
Internal structure of colonies:
- Valley walls are formed by lateral thickening of adjacent costoseptae.
- Valleys are floored by blistery plates (dissepiments) which occur repeatedly in vertical section through the colony.
Logan and Tomascik (1991) studied the growth rate of Diploria labyrinthiformis on several high latitude coral reefs around Bermuda. Growth rates showed an inverse curvilinear relationship with depth, with highest growth rates in shallow inshore waters and lowest at the edge of the Bermuda platform and on the adjacent fore-reef slope. Annual density bands formed seasonal couplets, with narrow, high density bands appearing to form in the spring-summer months and wider, low density bands over the rest of the year . Comparison of the extension rates of D. labyrinthiformis from Bermuda with published rates from lower latitudes indicates that reefs at lower latitudes (i.e., closer to the Equator) have higher extension rates than reefs at higher latitudes (Logan et al. 1994).
Evolution and Systematics
Systematics and Taxonomy
There are three described species currently placed in the genus Diploria. In addition to D. labyrinthiformis, these are D. strigosa, which is the most common and abundant of the three and has a growth habit similar to that of D. labyrinthiformis, and D. clivosa, which is mostly sub-massive and crustose with a distribution restricted to shallow, high energy, exposed reef platforms, back reef, and rocky habitats (Weil and Vargas 2010).
Molecular Biology and Genetics
Barcode data: Diploria labyrinthiformis
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Diploria labyrinthiformis
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
Diploria labyrinthiformis is listed as least concern on the IUCN Red List.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
Reasons: Widespread distribution in the tropical western Atlantic and occurs on most classes of marine hardbottom communities. Considered less threatened due to isolated reports of disease and moderate sensitivity to sedimentation stress.
There is no species specific population information available for this species. However, there is evidence that overall coral reef habitat has declined, and this is used as a proxy for population decline for this species. This species is more resilient to some of the threats faced by corals and therefore population decline is estimated using the percentage of destroyed reefs only (Wilkinson 2004). We assume that most, if not all, mature individuals will be removed from a destroyed reef and that on average, the number of individuals on reefs are equal across its range and proportional to the percentage of destroyed reefs. Reef losses throughout the species' range have been estimated over three generations, two in the past and one projected into the future.
The age of first maturity of most reef building corals is typically three to eight years (Wallace 1999) and therefore we assume that average age of mature individuals is greater than eight years. Furthermore, based on average sizes and growth rates, we assume that average generation length is 10 years, unless otherwise stated. Total longevity is not known, but likely to be more than ten years. Therefore any population decline rates for the Red List assessment are measured over at least 30 years. Follow the link below for further details on population decline and generation length estimates.
Global Short Term Trend: Relatively stable (=10% change)
Comments: Information is needed on the status and trend of extant populations.
In general, the major threat to corals is global climate change, in particular, temperature extremes leading to bleaching and increased susceptibility to disease, increased severity of ENSO events and storms, and ocean acidification.
Coral disease has emerged as a serious threat to coral reefs worldwide and a major cause of reef deterioration (Weil et al. 2006). The numbers of diseases and coral species affected, as well as the distribution of diseases have all increased dramatically within the last decade (Porter et al. 2001, Green and Bruckner 2000, Sutherland et al. 2004, Weil 2004). Coral disease epizootics have resulted in significant losses of coral cover and were implicated in the dramatic decline of acroporids in the Florida Keys (Aronson and Precht 2001, Porter et al. 2001, Patterson et al. 2002). Escalating anthropogenic stressors combined with the threats associated with global climate change of increases in coral disease, frequency and duration of coral bleaching and ocean acidification place coral reefs at high risk of collapse.
Localized threats to corals include fisheries, human development (industry, settlement, tourism, and transportation), changes in native species dynamics (competitors, predators, pathogens and parasites), invasive species (competitors, predators, pathogens and parasites), dynamite fishing, chemical fishing, pollution from agriculture and industry, domestic pollution, sedimentation, and human recreation and tourism activities.
The severity of these combined threats to the global population of each individual species is not known.
Degree of Threat: C : Not very threatened throughout its range, communities often provide natural resources that when exploited alter the composition and structure over the short-term, or communities are self-protecting because they are unsuitable for other uses
Comments: Considered less threatened with reports of disease, moderate resistance to sedimentation but low tolerance to eutrophication.
All corals are listed on CITES Appendix II.
Recommended measures for conserving this species include research in taxonomy, population, abundance and trends, ecology and habitat status, threats and resilience to threats, restoration action; identification, establishment and management of new protected areas; expansion of protected areas; recovery management; and disease, pathogen and parasite management. Artificial propagation and techniques such as cryo-preservation of gametes may become important for conserving coral biodiversity.
Having timely access to national-level trade data for CITES analysis reports would be valuable for monitoring trends this species. The species is targeted by collectors for the aquarium trade and fisheries management is required for the species, e.g., MPAs, quotas, size limits, etc. Consideration of the suitability of species for aquaria should also be included as part of fisheries management, and population surveys should be carried out to monitor the effects of harvesting. Recommended conservation measures include population surveys to monitor the effects of collecting for the aquarium trade, especially in Indonesia.
Biological Research Needs: Data needed on recruitment patterns. Information needed on susceptibility to eutrophication.
Global Protection: Few to several (1-12) occurrences appropriately protected and managed
Comments: Numerous occurrences in the Florida Keys National Marine Sanctuary, Biscayne National Park and Dry Tortugas, Florida.
Needs: Mooring buoys should be installed in marine protected areas.
Relevance to Humans and Ecosystems
There are no known negative impacts of this species.
Grooved brain coral helps to make up the coral reefs that serve as diving attractions.
Positive Impacts: ecotourism
Cohen et al. (2004) investigated the potential for using chemical and microstructural analysis of the skeletons of brain corals (Diploria labyrinthiformis) to provide proxy records of wintertime sea surface temperature (SST) variability in the subtropical North Atlantic. Although this species has a slow growth rate (less than one half of Pacific Porites species) and complex skeletal architecture, D. labyrinthiformis is an appealing potential archive of paleo-SST because of its abundance throughout the Caribbean; its tendency to build massive, long-lived colonies; and the presence of strong annual growth bands in the skeleton (Cohen et al. 2004).