Fire Coral Cuts and Stings Overview

Fire coral is related to jellyfish and anemones, and just like these creatures, it can really, really, sting. Learn to identify fire coral and then be sure to avoid it! Divers should be on the look out for fire coral in tropical and subtropical seas. 

Fire corals are not true corals. Fire corals (Millepora alcicornis) are members of the Cnidaria phylum, and although fire coral looks like coral, it is a member of the class Hydrozoa and more closely related to jellyfish and other stinging anemones. Fire corals are typically encountered off the Florida coast, in the Caribbean reefs and across the Bermuda platform. In addition, fire corals are sessile (fixed in one place) creatures that can attach to rocks, coral, seaweed, or pilings. The painful stings of M. alcicornis are inflicted using the cnidae (stinging threads), which are released from a cnidoblast on its surface. These are used to stun prey. Fire coral have minimal toxicity. These organisms inflict predominantly local pain, usually described as stinging or burning, and possible rash.

Fire corals have a bright yellow-green and brown skeletal covering and are widely distributed in tropical and subtropical waters. Scuba divers often mistake fire coral for seaweed, and accidental contact is common. The very small cnidoblast (an organ in some marine animals consisting of a minute capsule) on fire corals contain tentacles that protrude from numerous surface pores. In addition, fire corals have a sharp, calcified external skeleton that can scrape the skin.

Most Fire Coral Has White Tips

Fire coral is tricky -- it disguises itself in regular coral shapes. Divers have reported seeing fire coral in blade, branching, box, and even encrusting forms. As 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.

Fire Coral Has Visible Stingers

Most fire coral has visible stingers. Observant divers 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 a few millimeters away from a fire coral, when in reality he has already brushed against the tiny fire coral stingers.

Fire Coral Stings May Be Difficult to Identify

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 5 to 30 minutes after contact and, at first, the diver may not realize that he has been stung. Marine life injuries require a variety of treatments. When possible, divers should consult a doctor familiar with dive medicine to positively identify an injury as a fire coral sting.