Treating fire coral, hydroid and jellyfish stings

Ouch! Something stung me! It’s a common cry heard from swimmers and snorkellers. To positively identify each and every type of stinging creature on our shores would probably require a degree in marine biology and a whole lot more space than this column….I have neither.

One thing is for sure though, if you are stung by something in the water you can safely bet it was from the phylum Cnidaria (Ni-da’- ri -a). Cnidaria is a group of invertebrate animals that includes all corals, hydroids and jellyfish. The one common feature they share is that they all have stinging cells (cnidoblasts), commonly located in the tentacles; these characterize the phylum and give it its name.

Cnidarians take two body forms, polyp (corals and hydroids), and medusae (jellyfish). These forms sometimes occur as alternating stages in the life cycle of the animal. The phylum can be further broken down into three main classes; Hydrozoa (hydroids), Scyphozoa (jellyfish) and Anthozoa (corals).

Now for the good news – the vast majority of these creatures are completely harmless to humans and most varieties found here in the Caribbean produce only mild symptoms.

The stinging process from cnidaria resembles a jack-in-the-box mechanism. Mechanical stimulation such as touching the animal, and chemical stimulation such as removing the animal from its natural environment, will cause the cnidoblast to open its lid and fire a pressurized nematocyst into the victim to express venom.

First aid treatment for most fire coral, hydroid and jellyfish stings is the same. Rinse the affected area with seawater (do not use fresh water as this will cause the nematocyst to ‘fire’ again). Soak the area in 5 per cent acetic acid (vinegar) for 15-30 minutes to further de-activate the nematocysts.

After soaking, carefully remove any visible tentacles with tweezers and apply a topical antiseptic if available to inhibit infection. Pain is usually mild and eases quickly; however a cold compress can be applied to relieve pain if necessary (avoid using ice as the melting action may stimulate any remaining nematocysts).

Stings from cnidarians can be easily avoided simply by being careful in the water. Consider using goggles or a mask if you are swimming so you can see what is in front of you. When diving or snorkelling, remember the golden rule – look but don’t touch!