Staghorn Coral, Acropora cervicornis

Staghorn Coral, Acropora cervicornis. Underwater photograph taken in coastal waters off Bonaire, December, 2019. Photographs courtesy of Bob Hillis, Ivins Utah.

Staghorn Coral, Acropora cervicornis. Underwater photograph taken in coastal waters off Akumal, Quintana Roo, March 2021. Photograph courtesy of Marina Sutormina, Stockholm, Sweden.

Phylogeny:  The Staghorn Coral, Acropora cervicornis (Lamarck, 1816), is a hexacoral in the Acroporidae Family of Reef Corals. The genus Acropora is one of seven genera in this Family. This is a large genus, with one hundred and forty-three species. They are also known as the Deer Horn Coral.

Morphology:  Staghorn Coral polyps have radial symmetry, a hollow digestive cavity, and specialized stinging structures in tentacles surrounding the mouth. Their polyps have a flower-like appearance and produce a hard, calcareous skeleton. They live in tightly packed colonies. When multiple generations of these corals build upon the skeletons of previous generations, coral reefs are formed. They have cylindrical branches in groups of three, resembling deer antlers. Sub branches develop at right angles. Colonies of the staghorn coral are yellow, gold or brownish in color, with the tip of each branch having an enlarged polyp (terminal corallite), which is white or pale cream. Growth occurs by secondary corallites budding from the terminal corallite. Staghorn Coral branches are up to 2 m (6.5 feet) in length and 4.0 cm (1.5 inches) to 7.0 cm (2.75 inches) in diameter. These branches can increase length by 10 cm (3.9 inches) to 20 cm (7.9 inches) per year.

Habitat and Distribution: Staghorn Coral grows on hard substrates such as rocks, pilings, buoy chains, and wreckage. Due to their need for sunlight, they are found in relatively shallow water, from the very low intertidal zone to around 30 m (98 feet). Because the branches are somewhat fragile, they are located deep enough to avoid wave action. Staghorn Coral is a tropical Western Atlantic species and are found in Mexican waters of the Gulf of Mexico and the Caribbean from Tampico, Tamaulipas to Belize.

Diet:  Staghorn Corals are zooxanthellate. They have a symbiotic relationship with single-cell dinoflagellates, known as zooxanthellae. Zooxanthellae live within certain coral polyps, sea anemones, jellyfish, and nudibranchs. The zooxanthellae produce energy, during daylight, by means of photosynthesis. This energy is passed along to their hosts, sometimes providing up to 90% of the host’s total energy needs. In return, the host provides nutrients, carbon dioxide, and a secure, sunlit, platform for the zooxanthellae. During periods of chemical or thermal stress the corals can eject the zooxanthellae, to reduce metabolic stress. This causes the coral to appear white. This process is known as coral bleaching. Coral bleaching can be an indicator of an unhealthy environment, or a natural response to a short-term condition such as El Nino. The coral can replace the zooxanthellae after the stress is resolved, or it can acquire a different species of zooxanthellae that is better accommodated to the new environment. In either case, the polyp risks starvation if it is unable to replace the zooxanthellae quickly enough. Staghorn Corals supplement the energy provided by zooxanthellae by using their tentacles to capture amphipods and other plankton from the surrounding water. The tentacles then pass the food to the mouth. Because these polyps cannot change location, they are found in areas where moving water, caused by wave action or current, brings them more food.

Predators: Staghorn Corals are preyed upon by Damselfish, Bearded Fireworm, Hermodice carunculata, Coral Snails in the genus Coralliophyllia, Parrotfish, and Wrasses.

Reproduction:  Staghorn Corals are simultaneous hermaphrodites (having both male and female reproductive organs). Reproduction can be asexual, through fragmentation or budding, or sexual. Sexual reproduction occurs through broadcast spawning, with internal fertilization. The eggs hatch into planktonic planular larvae. The larvae that survive predation settle on a suitable hard surface and attach themselves by spreading out into a disk. They secrete a white starlike outer skeleton which cements itself to a spot and they then develop tentacles and grow into mature polyps.

Ecosystem interactions: Staghorn Coral plays an important role in the marine environment by providing habitat for numerous fish and invertebrate species. Also, reef building corals, such as Staghorn Coral, provide a wave barrier that protects coastal shorelines. In addition to the their symbiotic relationship with zooxanthellae, Staghorn Corals are known to host the parasitic bacteria, Candidatus Aquarickettsia rohweri. This bacteria slows coral growth, increases susceptibility to disease, and can create nutritional deficiencies.

Human Interactions: Historically, Staghorn Coral has been significantly harmed by human activities such as dredging, anchoring of vessels, water pollution, and aquarium and curio collecting. Staghorn Coral is now protected throughout all of its range and most of these threats have lessened. Now, most damage occurs inadvertently. All corals, including Staghorn Corals may be damaged by being covered by sediment or by being handled or stepped on by snorkelers, divers, or other beach goers. Any for of contact with the Staghorn Coral by humans should be avoided. From a conservation perspective the Staghorn Coral is currently consider to be Critically Endangered.

Synonyms: Acropora (Acropora) cervicornis, Acropora attenuata, Acropora muricata var. cervicornis, Heteropora cervicornis, Isopora muricata f. cervicornis, Madrepora (Eumadrepora) attenuata, Madrepora (Eumadrepora) muricata f. cervicornis, Madrepora attenuata, Madrepora cervicornis, and Madrepora muricata f. cervicornis.