Common name: boulder star coral

General information

The Boulder Star Coral, Montastraea annularis, is a prominent reef-building coral known for its role in constructing Caribbean coral reefs. It is characterized by its massive, dome-shaped colonies that can grow several meters in diameter. The coral polyps are usually extended at night, giving the colony a fuzzy appearance due to their long tentacles.

Historically, M. annularis was considered a single species, but genetic studies have revealed that it is a species complex, including Montastraea faveolata and Montastraea franksi. These corals are difficult to distinguish morphologically but have different ecological preferences and genetic compositions.

Care

Boulder Star Coral is a hardy species that can adapt to various light and flow conditions in the aquarium. However, it thrives best under moderate to high lighting and moderate water flow. It is important to maintain stable water parameters, particularly calcium and alkalinity levels, to support skeletal growth.

Feeding is not strictly necessary as M. annularis hosts zooxanthellae, symbiotic algae that provide most of its nutritional needs through photosynthesis. Supplemental feeding with planktonic foods can promote growth and health.

Symbiosis

Like many corals, M. annularis has a symbiotic relationship with zooxanthellae, which live within its tissues. The coral provides the algae with a protected environment and compounds necessary for photosynthesis. In return, the algae produce oxygen and help the coral to remove wastes. This relationship is crucial for the coral's survival and growth, especially in nutrient-poor tropical waters.

Habitat

M. annularis is native to the Caribbean Sea, the Gulf of Mexico, Florida, and the Bahamas. It typically inhabits reef slopes and is found at depths ranging from shallow waters to over 50 meters. The species prefers areas with clear water and strong sunlight to support its symbiotic zooxanthellae.