Bearded Fireworms: Avoiding and Treating Stings

A Painful Hazard of Ocean Diving

Bearded Fireworm (Hermodice caranculata)
Steve Simonsen / Getty Images

Oh, look! A furry little punk-rock caterpillar! The first time most underwater divers see a bearded fireworm, there can be an immediate impulse is to touch it. But, do not touch the fireworms! The bearded fireworm’s white bristles contain a potent venom.

Where to Find Fireworms

Bearded fireworms (Hermodice carunculata) are a type of bristle worm that can be found throughout the Caribbean, the tropical western Atlantic, and near some islands, such as Ascension Island in the Mid-Atlantic. They can be found pretty much anywhere in these zones. The fireworm's range begins near the water's surface and drops to 130 feet or deeper, and they can survive a great range of temperatures (from at least 66˚ F to 83˚ F).  Although they are tiny, between four and six inches in length, a sting from a bearded fireworm can be extremely painful, so be on the lookout for them at all recreational diving depths in regions where they are known to be present. 

Why Haven't I Seen a Fireworm?

Many divers have never seen a fireworm, even though they might be quite common in the waters they are diving. That's because the worms camouflage very well with corals, and can adopt any color from bright red-orange, to green-yellow, to brown. Fireworms are also timid creatures—although covered with poisonous bristles, they still hide all day long under rocks and rubble, often venturing out only in the cover of darkness.

You might spot a fireworm in the daytime slowly dragging its body across the coral. Fireworms eat coral by draping themselves over the coral tips and sucking the living coral animals out of their rocky skeletons. Keep your eyes peeled for fireworms anytime you see colorful, healthy coral with dead white tips, it is a good clue that they are nearby and you might get lucky and spot one.  But I repeat--no touching!

Outcomes of Touching a Fireworm

Instantly, you may feel foolish. You will understand immediately why it is called a fireworm since your finger (or wherever else you happen to brush against the worm) is now burning due to the tiny little spines on the fireworm's back that have now broken off in your skin along with the neurotoxin then contain. The pain will be severe and it will be instantaneous, but there is no reason to panic. The pain will last for a few hours and the irritation will likely last longer, but you will not die. The sting site will probably become red and inflamed, it may swell up, and you might experience some numbness in the area even after the pain subsides. More severe signs include dizziness and nausea, caused by the neurotoxin that is now circulating through your bloodstream. 

First Aid for Fireworm Stings

If you have been stung by a fireworm, you'll need to remove the spines and treat the area for pain and infection. Most diving first-aid kits will have tweezers to remove marine life spines, but it may be difficult or impossible to remove the tiny, transparent spines with tweezers. A good trick is to gently press sticky tape onto the affected area and then pull the tape away to remove the small spines.

Rubbing alcohol/ isopropyl alcohol or vinegar may help to alleviate the painful burning sensation caused by a bearded fireworm sting. Both alcohol and vinegar are standard in a diving first aid kit. If the irritation continues, hydrocortisone cream can be applied to the wound, and if an infection is suspected, a topical antibiotic can be applied. Take ibuprofen or acetaminophen for the pain. If the pain is severe, does not go away, or infection is suspected, get yourself to a doctor knowledgeable in marine life injuries, or call the Diver's Alert Network (DAN) Hotline for advice.

Avoid Fireworm Stings in the Future

All you need to do to avoid fireworm stings is good buoyancy and a little awareness. A fireworm will not leap off the coral and fling itself at you! They move slowly and are not aggressive towards divers. If a fireworm feels threatened, you'll know. It will puff out its bristles to protect its back. A diver can observe this effect by waving water at fireworm, carefully.

Simply swim well away from coral beds to avoid accidentally brushing against a fireworm’s painful bristles. If you are worried about marine life stings, a good precaution is to wear a full wetsuit or lycra diving skin as protection against accidental contact with creatures.