Biology and IdentificationFire coral, which belong to the genus Millepora, are found in tropical and subtropical waters around the world. Generally fire coral adopts a yellow-green or brownish branchy formation, although its external appearance often varies due to environmental factors. Because fire coral can colonize hard structures, it can even adopt a rather stony appearance with rusty coloration.
Despite their calcareous structure, fire coral is not a true coral; these animals are more closely related to Portuguese man-of-war and other hydrozoans.
Mechanism of InjuryFire coral gets its name because of the fiery sensation experienced after coming into contact with a member of the species. The mild to moderate burning that it causes is the result of cnydocites embedded in its calcareous skeleton; these cnydocites contain nematocysts that will fire when touched, injecting their venom.
Signs and SymptomsThe burning sensation may last several hours and is often associated with a skin rash that appears minutes to hours after contact. This skin rash can take several days to resolve. Often, the skin reaction will subside in a day or two, but it may likely reappear several days or weeks after the initial rash disappeared.
Fire-coral lacerations, in which an open wound receives internal envenomation, are the most problematic fire-coral injuries. Venom from Millepora spp. is known to cause tissue necrosis on the edges of a wound. These injuries should be carefully observed, as necrotic tissue provides a perfect environment to culture serious soft tissue infections.
- Avoid touching these calcareous formations.
- If you need to kneel on the bottom, look for clear sandy areas.
- Remember that hard surfaces such as rocks and old conchs may be colonized by fire coral even if they do not look branchy.
- Always wear full-body wetsuits to provide protection against the effects of contact.
- Master buoyancy control.
- Always look down while descending.
- Rinse the affected area with household vinegar.
- Redness and vesicles will likely develop. Do not puncture them; just let them dry out naturally.
- Keep the area clean, dry and aerated — time will do the rest.
- For open wounds, seek a medical evaluation.
NOTE: Fire-coral venom is known to have dermonecrotic effects. Share this information with your physician before any attempts to suture the wound, as the wound edges might become necrotic.
- Antibiotics and a tetanus booster may be necessary.