When the subject of dangerous marine creatures comes up sharks are usually the first to be mentioned; 20 years later, the memory of Jaws lingers on. Actually, sharks are on the low end of the 'danger' scale. Of the more than 250 species of sharks identified, only about 40 pose any danger to humans.
Underwater injuries are rarely intentional attacks. Most are caused by accidental collisions with the razor sharp edges of a coral head, the venom-filled spines of a scorpionfish or stingray, the stinging nematocysts of jellyfish or fire coral, or the piercing daggers of a fireworm or sea urchin.
Space and food are always in demand on the reef, creating a fiercely competitive environment. Each creature existing in this battlefield survives by using a specific attack strategy and method of defense. Many critters use camouflage, some travel in dense schools, others have developed an arsenal of weapons and deadly poisons. Luckily, few possess toxins lethal enough to kill humans; unfortunately, there are some that can cause a great deal of pain and discomfort. The good news is if you know what to look for, all can be easily avoided.
Hydroids are responsible for most snorkeling injuries; the culprits are usually fire coral, the Portuguese Man-of-War and jellyfish; all members of the phylum Cnidaria. Fire coral is one of the greatest nuisances because it is incredibly prolific and grows in a variety of forms; branching, upright and encrusting, often resembling true coral. Its smooth texture and tan coloring often make it invisible to snorkelers who accidentally brush up against the poisonous dart-like nematocysts that blanket its surface. Contact with fire coral causes painful welts on exposed skin but the sting of the Portuguese Man-of-War is dangerous. Iridescent blue gas-filled floats make this hazard easy to identify but the long strands carrying the nematocysts can extend more than 40 feet so it is occasionally felt before it is seen.
Treatment for all Cnidarian stings is essentially the same: Do not rub the wound or rinse it with fresh water; this will only activate any remaining nematocysts and cause more pain. Remove any tentacles with a towel or tweezers and flush it thoroughly with sea water. A dilute solution of alcohol or vinegar should be applied to help dissolve any remaining nematocysts. A paste of lime juice and meat tenderizer may also be beneficial, however, this particular treatment can occasionally cause extreme dermatitis, so use caution.
Some of the most common underwater injuries are caused by relatively sedentary critters such as sea urchins and fish belonging to the family Scorpaenidae, which includes scorpionfish, stonefish and lionfish. Scorpionfishes and their relatives are not aggressive but they are well armed; a potent poison is stored in sacs at the base of their dorsal spines. Scorpionfish only use their weapons defensively. However, because of their uncanny ability to blend in with their surroundings, they occasionally go unnoticed until it's too late. Scorpionfish wounds are painful and allergic reactions can sometimes develop. Soaking the injury in hot water for 30 to 90 minutes will usually reduce the pain and swelling. If the sting produces a severe reaction, seek medical attention as soon as possible.
Although most urchin spines do not contain poison, they are sharp and brittle and often break off under the skin. The spines are difficult to remove because of countless tiny barbs pointing upward toward the tip. Soaking the injury in the hottest water you can stand is the recommended remedy to relieve pain. You can try removing the spines with tweezers but it's likely some will remain. The body will naturally break the spines down in a few days; meat tenderizer or a dilute vinegar solution may speed up the process.
Fireworms (also called bristleworms) can cause a similar affliction. The white bristle-like structures, called setae, covering the bodies of these colorful segmented worms are sharp and venomous, causing pain, irritation and numbness. It is virtually impossible to remove embedded fireworm spines, they work their way into the skin like strands of fiberglass. The best way to treat this wound is to thoroughly dry the affected area with a hair dryer, if available, then use tape to remove any exposed pieces. A dilute solution of vinegar, ammonia or isopropyl alcohol will help the spines dissolve more quickly; meat tenderizer may also help. Rubbing aggravates the injury.
Stingrays present snorkelers with another underwater hazard they need to be aware of. So named for a sharp barb on their tails, stingrays will often bury themselves in sand, becoming virtually invisible from the surface. Although stingrays are not naturally aggressive, they will occasionally sting swimmers and snorkelers who accidentally stumble across them while wading through shallow water. These injuries can be serious, depending on the size and depth of the incision. The venom can cause great pain and, in extreme cases, sweating, faintness, muscle cramps and irregular or rapid heartbeat. Wash the wound thoroughly and soak it for 30 to 90 minutes in hot water. Watch the victim closely and, if serious symptoms begin to appear, seek medical attention immediately.
It's rare but fish bites do occur, usually during fish feeding fiascoes. Reef fish are inherently non-aggressive toward humans, however, moray eels, groupers and Barracuda have, on occasion, been known to mistake fingers for food. The best way to avoid accidents during these scenarios is to remove all shiny jewelry before entering the water and leave the feeding to the experts. Fish bites vary in severity; in all cases it's imperative the wound be washed thoroughly and treated with topical antibiotic to prevent infection.
Few marine injuries are severe enough to require professional medical attention. However, every situation is different and needs to be evaluated accordingly. If the injury is severe or persistent, consult a physician. A first aid kit stocked with vinegar, rubbing alcohol, meat tenderizer, hot water, antibiotic salve, adhesive tape, aspirin, gauze bandages and tweezers, will give you all the tools you'll need to treat most marine injuries. As always, prevention is always the best medicine; wear a protective full-body dive suit and follow one simple rule: If you don't know what it is, don't touch it!