Staghorn Coral (Acropora cervicornis): Facts and Threats

What is staghorn coral?

Staghorn coral is not a plant or a rock but a colony of animals. Each colony is made of thousands of tiny polyps, soft sac-shaped animals a few millimeters across with a ring of stinging tentacles around the mouth. Corals belong to the cnidarians, the group that also includes sea anemones and jellyfish; the details are in is coral a plant or an animal?

Every polyp in a colony is a genetic copy of the others, and they are all linked by a thin sheet of living tissue. Together they lay down a hard skeleton of aragonite, a form of calcium carbonate, which becomes part of the reef when the coral dies.

Staghorn coral is one of only two Acropora species in the Atlantic, the other being the elkhorn coral (A. palmata). The two sometimes interbreed, producing a hybrid known as fused staghorn coral (A. prolifera). In the Indo-Pacific, by contrast, there are more than 100 Acropora species, many of them also called staghorn corals.

What does staghorn coral look like?

Staghorn coral grows as upright or spreading cylindrical branches, about 2.5–7.5 cm (1–3 in) thick, that fork again and again like the antlers of a stag. Living colonies are golden tan, beige or pale brown, sometimes with a greenish or purplish tint, and the growing tips are white. The color comes from algae living inside the coral’s tissue.

Single colonies can grow to at least 1.2 m (4 ft) tall and 1.8 m (6 ft) across, and some exceed 2 m (6.6 ft). Where conditions are good, neighboring colonies merge into dense, interlocking stands called thickets, which once covered large areas of shallow reef. Before the 1980s, staghorn coral was so dominant in parts of the Caribbean that reef scientists named a whole reef zone after it.

Habitat and range

Staghorn coral lives in the tropical western Atlantic. Its range covers the Florida Keys and southeast Florida, the Bahamas, the islands of the Caribbean, the Caribbean coasts of Central and South America, and the southwestern Gulf of Mexico. Its northern limit is Palm Beach County, Florida, where it is rare. It is absent from Bermuda and from the US part of the Gulf of Mexico.

It needs clear, warm, sunlit water and is usually found between about 5 and 18 m (15–60 ft) deep. Typical habitats include fore reefs on the seaward side, back reefs and lagoons behind the reef crest, patch reefs, spur-and-groove formations and flat limestone hardbottom.

How does staghorn coral feed?

Like most reef-building corals, staghorn coral gets most of its food from partners living inside it. Its tissue is packed with single-celled algae called zooxanthellae, as many as a million or more per square centimeter. The algae use sunlight to make sugars and other nutrients, and they pass most of them to the coral, supplying up to about 90 percent of its energy needs. In return, the coral gives the algae shelter, carbon dioxide and nutrients from its waste.

The polyps also hunt. Mostly at night, they extend their tentacles and use stinging cells to catch zooplankton, tiny animals drifting in the water, and pull them into the mouth. This extra food supplies nitrogen and other nutrients that the algae cannot provide.

Because it depends on its algae, staghorn coral needs clear, sunlit water. If the water becomes too hot, the partnership breaks down and the coral turns white, a process explained in what is coral bleaching?

How fast does staghorn coral grow?

Healthy staghorn coral is one of the fastest-growing corals in the Atlantic. According to NOAA Fisheries, its branches can grow up to about 20 cm (8 in) a year, many times faster than the slow-growing boulder and brain corals. New polyps form at the tip of each branch, behind a large axial polyp that leads the growth.

This speed made staghorn thickets important reef builders. Over the last 5,000 years, staghorn coral, elkhorn coral and the large star corals built much of the framework of Caribbean reefs. Dense thickets also break the force of waves before they reach the shore and provide shelter for young fish, lobsters, crabs and many other animals.

How does staghorn coral reproduce?

Staghorn coral reproduces in two ways. The most common is fragmentation. Storms, waves or passing animals break off branches, and if a fragment lands on a suitable surface it can attach and grow into a new colony. Whole thickets can spread this way, although every colony formed from fragments is a clone of its parent.

Once a year, staghorn coral also reproduces sexually. Each colony is a simultaneous hermaphrodite, producing both eggs and sperm, but it usually cannot fertilize itself. A few nights after a full moon in late summer, usually in July or August, colonies across a reef release their eggs and sperm into the water at the same time, an event called broadcast spawning. Fertilized eggs develop into tiny swimming larvae that drift for several days before settling on hard ground and founding new colonies. Colonies become mature at about 17 cm (7 in) tall.

In the wild today, very few larvae survive to become colonies, so the species relies heavily on fragmentation. The whole process is described in how do corals reproduce?

Staghorn coral and other reef life

A healthy staghorn thicket works like an apartment block for reef animals. The maze of branches gives shelter to schools of small fish such as grunts, damselfish and young snappers, which hide among the branches by day and spread out to feed at night. Spiny lobsters, crabs, brittle stars and many small invertebrates live in the spaces underneath.

Some animals depend on the coral more directly. The threespot damselfish defends a small territory inside the thicket, and many fish shelter there until they are big enough to move to open reef. Studies generally find that reefs with more branching coral support more fish, which is one reason why restoring staghorn coral matters for the whole reef and for the fisheries and tourism that depend on it.

Predators and threats

Disease has been the greatest single cause of decline. White band disease, first seen in 1979, strips the living tissue from staghorn and elkhorn branches, leaving a band of bare white skeleton that moves up the branch. It caused the loss of about 97 percent of staghorn coral across its range from the early 1980s. Unlike many other Caribbean corals, staghorn coral appears to be resistant to stony coral tissue loss disease, which spread through Florida from 2014.

Rising sea temperatures are now the greatest threat. Marine heatwaves cause bleaching that can kill whole populations. In 2023, record ocean heat struck Florida’s reefs, and a study published in 2025 found that 98–100 percent of the surveyed staghorn and elkhorn colonies in the Florida Keys and Dry Tortugas died, leaving both species functionally extinct on Florida’s reef.

Other threats include ocean acidification, which makes it harder to build skeleton; pollution and runoff from land; storms that smash thickets faster than they can regrow; and overfishing of plant-eating fish, which lets seaweed smother reefs. The die-off of the long-spined sea urchin, a key algae grazer, across the Caribbean in 1983 made this problem worse. Natural predators include fireworms, the coral-eating snail Coralliophila abbreviata and the threespot damselfish, which kills patches of coral tissue to farm algae on the bare skeleton.

Conservation status

The IUCN Red List classifies staghorn coral as Critically Endangered. In the United States, it was listed as threatened under the Endangered Species Act in 2006, together with elkhorn coral, the first corals ever listed under the act. Critical habitat was designated in 2008 in Florida, Puerto Rico and the US Virgin Islands, and NOAA published a recovery plan for both species in 2015. NOAA estimates the remaining population at less than 3 percent of its former abundance, mostly in isolated colonies rather than thickets.

Restoration: growing staghorn coral in nurseries

Because it grows fast and survives being broken, staghorn coral became the main species used in coral restoration in the Caribbean. Since the mid-2000s, groups such as the Coral Restoration Foundation in the Florida Keys have grown small fragments in underwater nurseries, often hanging them from tree-like frames, and then cemented the young colonies onto damaged reefs. Tens of thousands of staghorn colonies have been planted out in Florida alone.

Results have been mixed. Many planted colonies grow well at first, but long-term survival has often been low because of disease, heat and predators. During the 2023 heatwave, teams moved many nursery corals to deeper water or to tanks on land to save their genetic diversity. Restoration now focuses on finding heat-tolerant genotypes and on restoring whole reef communities, as described in what is happening to Florida’s coral reefs?

Myths and facts

Myth: Coral is a kind of rock. The hard skeleton is limestone, but it is built by living animals, and only a thin layer of living tissue covers it. When the tissue dies, the white skeleton is left behind.

Myth: Broken coral is dead coral. In staghorn coral, the opposite is often true. A broken branch that lands in a good spot can survive and grow into a new colony, which is exactly how restoration nurseries multiply it.

Fact: Touching coral harms it. The living tissue is a thin, delicate layer, and contact from hands, fins or anchors can damage it and let disease in. Divers and snorkelers help most by looking without touching.