Mussa angulosa

Lore & Background

Mussa angulosa is a colonial species that forms low domes up to 50 cm across. Its corallites are phaceloid, tubular, and grow in series of one to three, occasionally up to five. Individual corallites are large, 25 to 45 mm in diameter and up to 6 mm high, with four cycles of narrow, curved, widely spaced septa. The polyps are very large, sometimes reaching 12 cm in length and 4 cm in diameter, completely obscuring the short branches of the stony skeleton. During the day the polyps appear fleshy; at night they expand further and are fringed by a rim of short tentacles. Their color varies, being grey or pale brown with green, pink, and purple shades. The tissues contain symbiotic zooxanthellae, which photosynthesize and provide organic compounds to the coral.

This coral is aggressive, attacking other fast-growing corals that grow nearby and threaten to overgrow or shade it. Its cnidocytes are so powerful that no other Caribbean corals can successfully attack it. It leans away from the current as it grows and reacts adversely to increased sedimentation. It is a reef-building species.

Reader's Guide

Mussa angulosa is notable as the only species in its genus and for its aggressive dominance on Caribbean reefs. Its cnidocytes are uniquely powerful among Caribbean corals, allowing it to fend off overgrowth from faster-growing species. The coral's large, fleshy polyps and variable coloration make it visually distinctive. It is a reef-building species, contributing to the structural complexity of shallow reef habitats. The IUCN Red List lists it as near threatened, with no specific threats identified, but it is likely declining due to general reef degradation from mechanical damage, climate change, and ocean acidification. It is susceptible to coral bleaching and diseases that affect stressed corals. Off the coasts of the United States, it occurs in marine parks and conservation areas where it is protected. Its presence across the Caribbean, Bahamas, and Gulf of Mexico, and its depth range of 3 to 60 meters, indicate a broad but shallow-water distribution.

Did You Know?

• Mussa angulosa is the only species in the genus Mussa.
• No other Caribbean coral can successfully attack it due to its powerful cnidocytes.