The boulder brain coral (Colpophyllia natans) is named for its large, boulder-like colonies, the surfaces of which are covered in a meandering pattern of curved, brown ridges, separated by tan, green or whitish depressions, known as valleys (3)(4)(5)(6). Colonies may form large domes up to two metres in diameter, but can also grow as large, rounded plates (3)(4)(5). The boulder brain coral generally has long, wide valleys, up to two centimetres across, and wide ridges, which have a fine but distinct groove along the top (3)(4)(5)(6). Boulder brain coral colonies are often eroded at the base, forming overhangs (6).
Like all corals, the colonies of this species are composed of numerous tiny, anemone-like animals known as polyps, which possess a sac-like body and a central ‘mouth’, surrounded by tentacles (3). In the boulder brain coral, the tentacles are only extended at night (3)(4). Although generally considered to be the only species in the genusColpophyllia, some colonies of the boulder brain coral possess short valleys containing only one to three polyps(3), and are considered by some to be a separate species, Colpophyllia breviserialis (closed-valley brain coral) (4)(5). The boulder brain coral can be distinguished from the similar Diploria brain corals by its wider valleys and ridges (3)(5).
Also known as
giant brain coral, large grooved brain coral, large-grooved brain coral.
The boulder brain coral is a zooxanthellate coral, meaning that it has symbioticalgae, known as zooxanthellae, living within its tissues. The zooxanthellae provide the coral with nutrients produced by photosynthesis, and in return receive a safe and stable environment in which to live. Although this limits zooxanthellate corals to living in relatively clear, shallow, warm waters where photosynthesis can take place, it allows them to grow faster and create large reef structures, formed by the laying down of the coral’s hard skeleton (3)(8). The boulder brain coral is also able to actively feed on tiny zooplankton, caught using stinging cells on the tentacles (3).
Like other corals, the boulder brain coral is able to reproduce asexually in a process known as budding, in which polyps divide into two or more new polyps. It is also capable of sexual reproduction, releasing eggs and sperm into the water for external fertilisation(3). The boulder brain coral is a hermaphrodite, meaning that each polyp produces both eggs and sperm (9). In some areas, studies have found this species to spawn in August and September, at a very specific time (shortly after sunset), which remains remarkably consistent between years (9). Fertilised eggs develop into larvae, which drift in the water column before settling and developing into polyps(3). The boulder brain coral is an aggressive species, which is able to dominate neighbouring corals by extruding filaments which digest the tissues of its competitors. This strategy helps the boulder brain coral to successfully compete for space on the reef (10).
Although the boulder brain coral is currently widespread and relatively common throughout its range, it is likely to be facing a number of threats (1). Of particular concern are coral diseases, such as black-band disease and white plague (1), which can cause large mortality in some areas (11)(12)(13). Elevated water temperatures in the Caribbean in 2005 also caused mass coral bleaching, in which the stressed corals expel their zooxanthellae, often leading to death. Although many boulder brain coral colonies initially showed signs of recovery after this event, the weakened corals were subsequently affected by an outbreak of disease (14)(15). Other specific threats to the boulder brain coral include predation by species such as the stoplight parrotfish (Sparisoma viride) and three-spot damselfish (Stegastes planifrons), as well as sedimentation (1).
The boulder brain coral is also likely to be susceptible to the many threats faced by corals worldwide, including the major threat of climate change, which can lead to more frequent and severe storms and increase coral bleaching, as well as increased ocean acidity, which can affect the ability of a coral to lay down its hard skeleton. More localised threats to corals include destructive fishing practices, human development, invasive species and pollution (1)(8)(16)(17).
All corals are listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning international trade in corals should be carefully regulated (2). The boulder brain coral may also receive some protection within a number of Marine Protected Areas, such as the Florida Keys National Marine Sanctuary, Dry Tortugas National Park and Flower Garden Banks National Marine Sanctuary, USA (1). In addition, it is illegal to harvest corals commercially in US waters (1).
With an estimated 20 percent of coral reefs already lost worldwide (17), and around a third of reef-building corals threatened with extinction (16), the conservation of these vital ecosystems is now urgent. Recommended measures for protecting this and other coral species include further research and monitoring, the expansion of protected areas, building awareness, disease research and efforts to tackle global climate change (1)(8)(17).
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Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.
Type of asexual reproduction (reproduction that does not involve the formation of sex cells), in which new individuals develop from the parent organism, forming a swelling similar in appearance to a bud. The ‘bud’ slowly separates from the parent as it grows.
A group of organisms living together. Individuals in the group are not physiologically connected and may not be related, such as a colony of birds. Another meaning refers to organisms, such as bryozoans, which are composed of numerous genetically identical modules (also referred to as zooids or ‘individuals’), which are produced by budding and remain physiologically connected.
The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
Possessing both male and female sex organs.
Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Metabolic process characteristic of plants in which carbon dioxide is broken down, using energy from sunlight absorbed by the green pigment chlorophyll. Organic compounds are made and oxygen is given off as a by-product.
Typically sedentary soft-bodied component of cnidaria, a group of simple aquatic animals including the sea anemones, corals and jellyfish. A polyp comprises a trunk that is fixed at the base, and a mouth that is placed at the opposite end of the trunk and is surrounded by tentacles.
The production or depositing of large quantities of eggs in water.
Describes a relationship in which two organisms form a close association. The term is now usually used only for associations that benefit both organisms (a mutualism).
Tiny aquatic animals that drift with currents or swim weakly in water.
Vize, P.D., Embesi, J.A., Nickell, M., Brown, D.P. and Hagman, D.K. (2005) Tight temporal consistency of coral mass spawning at the Flower Garden Banks, Gulf of Mexico, from 1997-2003. Gulf of Mexico Science, 23(1): 107-114.
Ferriz-Domínguez, N. and Horta-Puga, G. (2001) Short-term aggressive behavior in scleractinian corals from La Blanquilla reef, Veracruz Reef System. Revista de Biología Tropical, 49(1): 67-75.
Nugues, M.M. (2002) Impact of a coral disease outbreak on coral communities in St. Lucia: what and how much has been lost? Marine Ecology Progress Series, 229: 61-71.
Croquer, A., Pauls, S.M. and Zubillaga, A.L. (2003) White plague disease outbreak in a coral reef at Los Roques National Park, Venezuela. Revista de Biología Tropical, 51(4): 39-45.
Whelan, K.R.T., Miller, J., Sanchez, O. and Patterson, M. (2007) Impact of the 2005 coral bleaching event on Porites porites and Colpophyllia natans at Tektite Reef, US Virgin Islands. Coral Reefs, 26: 689-693.
Miller, J., Muller, E., Rogers, C., Waara, R., Atkinson, A., Whelan, K.R.T., Patterson, M. and Witcher, B. (2009) Coral disease following massive bleaching in 2005 causes 60% decline in coral cover on reefs in the US Virgin Islands. Coral Reefs, 28: 925-937.
Carpenter, K.E. et al. (2008) One-third of reef-building corals face elevated extinction risk from climate change and local impacts. Science, 321: 560-563.
Wilkinson, C. (2008) Status of Coral Reefs of the World: 2008. Global Coral Reef Monitoring Network and Reef and Rainforest Research Center, Townsville, Australia. Available at: http://www.gcrmn.org/status2008.aspx
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