Animal-World > Coral Reef > Small Polyped Stony > Staghorn Coral

Acropora formosa
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Scientific name: Acropora formosa

Distribution: Acropora formosa is found in the Pacific and Indian Oceans and the Red Sea.

In the wild, Acropora formosa are found on the reef slopes, fringes, and lagoons and usually in thickets with a single species spreading as far as ten metres (approximately 32.8 feet). Acropora formosa are commonly found along with Acropora nobilis and Acropora grandis. Acropora formosa is frequently a dominant species.

Description: All Acropora spp. corals have very porous and lightweight skeletons near the edges of the coral and the tips (branches). The bases, on the other hand, are very dense. Acropora formosa, along with Acropora cervicornis, has the densest base skeletons ever recorded in stony corals.

Acropora spp. corals are characterized by fast growing terminal (or axial) polyps at the tips of the branches. These terminal polyps do not have zooxanthellae. They grow quickly because the terminal polyps are fed by the rest of the colony. This allows Acropora to outgrow other corals on the reef.

Acropora are found in a great range of colors - blue, pink, purple, orange, green, yellow. Many have golden-brown structures with pale tips in white, pink, purple, blue, or green.

Acropora formosa is a Branching or Arborescent Acropora. It is a staghorn type of Branching Acropora, hence it's most popular common name. It is considered a favorite of reef aquarists (per Eric H. Borneman in Aquarium Corals: Selection, Husbandry, and Natural History).

In the wild, Acropora formosa found in shallow water have short and compact branches and specimens found in deep water have more open branches.

Background: Acropora are from the Subclass Zoantharia and the Order Scleractinia. The family Acroporidae was erected by Verrill in 1902. The scientific name Acropora spp. is credited to Oken in 1815. Acropora formosa is credited to Dana in 1846.

As a whole, the many Acropora spp. corals are commonly called simply Acropora. The individual Acropora corals have many common names, usually based on their growth forms. Some of the common names include staghorn, cat's paw, bottlebrush, table, tabletop, finger, and so on. These common names are often used on many different species of Acropora which can quickly result in confusion.

Aquarium Care: Acropora need to be carefully acclimated to their new homes. They need to be placed in their permanent position within a tank after acclimation. Moving Acropora from place to place will stress them.

Excellent and stable tank conditions are required to keep all Acropora spp. corals. Tanks should offer high calcium levels and strontium should be added. A mature tank (well over a year old) is advised to increase the chance of successfully keeping Acropora.

There are many animals that will prey on Acropora spp. corals. Some Acropora have symbiotic relationships with crabs and shrimps that may help them against predators. Other hitchhikers may actually be predators so careful observation must be done.

Many Acropora spp. corals have been propagated by fragmentation. It is not difficult to find captive-bred colonies of Acropora spp. corals for sale or trade. Captive-bred corals may tolerate less intense lighting and water movement as well as possibly being easier to care for than those taken from the wild.

Brown, bottlebrush, and thin-branched Acropora are considered the most tolerant of aquarium conditions. Tabletop Acropora are the most difficult to keep in the home aquarium. The staghorn type, which Acropora formosa is, is somewhere in between the two.

Staghorn type Acropora grow rapidly and are considered to be among the most rapid growing of the stony corals. They fragment easily and the fragments can form new colonies. This makes them ideal candidates for captive breeding/propagation.

Lighting: High / Intense.

Water flow: High. According to Eric H. Borneman in Aquarium Corals: Selection, Husbandry, and Natural History, "... all Acropora seem to prefer a strong, random, mixing-type current ..." therefore a rotating powerhead or wavemaker setup is recommended.

Difficulty of Care: In the wild, Acropora spp. corals are found across the reef in various locations from turbid waters (with sediment or foreign particles stirred up or suspended in the water) to those with strong waves and high currents; from areas where there is little light to being fully exposed to the sun (and the air) at low tide.

With their natural habitat an array of conditions, it is surprising to find that Acropora spp. corals are among the more difficult to keep in captivity. They require stable tank conditions - sudden changes may result in death. They are sensitive to temperature changes, sedimentation, chemical and other environmental stresses. They do not tolerate being moved around in the tank.

Signs of stress are bleaching and receding and they will diminish and die rapidly. They are also susceptible to almost every coral disease including white-band disease, black-band disease, necrosis, etc. Acropora is particularly susceptible to rapid tissue necrosis (RTN), especially specimens from the wild.

Transporting Acropora spp. corals can also be a problem because of their shapes, the easily broken outer edges of the coral skeleton, and the ease with which they become stressed.

Availability: Acropora formosa is a very difficult coral to find for sale at online retailers. Very few specimens can be found and those were listed as staghorn corals, not Acropora formosa so the exact species is suspect. Prices vary based on size and color. Prices range from $10.00 for frags to $80.00. It's availability for purchase conflicts with the research showing it as a common and abundant coral on the reef, it's ease of propagation by fragmentation, and it's popularity with hobbyists.

by Elizabeth M. Lukan, July 13, 2006

author of:
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