How to Identify Fire Coral and Treat Its Stings

The fire coral (Millepora dichotoma) is not a true coral at all, but a colony-forming marine organism related to jellyfish and anemones. It is more properly known as a hydrocoral. Like jellyfish, the sea coral can inflict painful stings. Divers in tropical and subtropical waters should learn how to identify this organism and avoid it. 

If you learn some of the key characteristics to be on the lookout for, you may be able to avoid the fire coral altogether, but you should know how to treat the sting if you're unfortunate enough to get one. 

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Know Fire Coral's Colors

Back lit fire coral
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Fire coral is tricky—it disguises itself in regular coral shapes and is often mistaken for seaweed. Divers have reported seeing fire coral in blade, branching, box, and even encrusting forms. Because fire coral is easily confused with other corals, color is a good way to identify it.

Most fire coral is a brownish-orange or brownish-green. It frequently has white tips.

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Visible Stingers

Fire Coral Polyps
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Most fire coral have visible stingers. Observant divers who get a close look may notice the coral's transparent, hair-like stingers sticking out from fire coral like tiny cactus spines.

The fact that the stingers are hard to see is one of the reasons fire coral stings are so common. A diver may think he is still a few millimeters away from a fire coral when, in reality, he has already brushed against the tiny stingers.

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Avoiding Fire Coral Stings

Freckled Hawkfish in fire coral
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To prevent fire coral stings, divers should stay far enough from the reef to avoid even accidental contact. Many apparently benign reefs conceal fire coral.

But unexpected events may cause even the most careful diver to inadvertently brush against the reef. Wearing a full wetsuit, or even a thin spandex dive skin, helps protect a diver swimming in an area with fire coral.

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Identifying a Sting

Underwater World of Red Sea.
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Fire coral cuts appear as rashes or red welts and are extremely painful. Fire coral stings may be difficult to diagnose because they do not begin to burn until up to a half-hour after contact, and the diver may not realize at first he has been stung.

Injuries inflicted by marine life can require a variety of different treatments, depending on severity. When possible, divers should consult a doctor familiar with dive medicine to positively identify an injury as a fire coral sting.

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Treating Fire Coral Injuries

Coral beauty and colors
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To treat fire coral stings, experienced divers recommend a variety of remedies, but here is a widely accepted method:

  1. Rinse with seawater. Avoid fresh water because it will increase the pain.
  2. Apply topical acetic acid (vinegar) or isopropyl alcohol.
  3. Remove the tentacles with tweezers.
  4. Immobilize the extremity. Movement may cause the venom to spread.
  5. Apply hydrocortisone as needed for itching. Discontinue immediately if any signs of infection appear.
  6. If no signs of allergic reaction are present, the pain may be relieved with an over-the-counter pain medication, like ibuprofen. 
  7. If the diver develops shortness of breath; swelling of the tongue, face, or throat; or other signs of an allergic reaction, treat him for an allergic reaction and seek immediate medical attention. While rare, severe allergies do happen.