Branching Fire Coral

• Contact with it produces an intense, immediate burn that can last for days: its stinging polyps are minute and protrude through tiny pores, invisible to the naked eye.
• It is a hydrozoan, not an anthozoan: it has a medusa stage in its cycle, which no true coral has.
• It contributes substantially to building the Caribbean reef and is among the first organisms to colonise new surfaces.
• It is not a true coral: it is a hydrozoan, more closely related to jellyfish and the Portuguese man o' war than to stony corals, although it builds just as solid a calcareous skeleton.
• Its sting causes an intense, immediate burning, hence the name fire coral. It is one of the commonest mishaps among Caribbean divers.
• The surface looks smooth but is pierced by minute pores from which polyps bearing stinging cells protrude, invisible to the naked eye.
• It is opportunistic: it grows over sea fans, sponges and other corals, taking on their shape, which makes it hard to identify.
• It hosts zooxanthellae and bleaches as the water warms, just as stony corals do.

Habitat and environment

Shallow, well-lit reefs of the Caribbean and the tropical Atlantic

Sources consulted: Linneo (1758); Lewis (2006); Smithsonian Marine Station