Sea Jellies (also know as Jellyfish) are found in all oceans, from the equator to the poles, from shallows to the deep sea. They can range in size from less than an inch to over six feet across. Most jellies are predators, capturing small fish with their stinging tentacles. However, some jellies are “farmers,” soaking up food chemicals produced by symbiotic algae that live within their tissues. There are about 200 species of jellies world-wide — some are ocean drifters, others are found in quiet bays and lagoons.
Individual jellies are circular and symmetrical, with a ring of tentacles around the central mouth. The tentacles have stinging cells that are used for food capture and defense.
Portuguese Man-of-War, which are related to jellyfish, but can’t swim, can also be found at times on Kauai. They can also have stinging cells in the form of a long nematocyst thread.
Swimmers should always be alert when Jellies or Man-of-war are present since some people are quite sensitive even to mild Jelly stings. If stung by a jellyfish, many lifeguards and doctors recommend rinsing the area with seawater, or applying vinegar to the sting to deactivate the toxin. However, vinegar is thought to make stings from a man-of-war worse, so try to determine what type of animal you’re dealing with.
After rinsing the area well, carefully remove any part of the animal that still clings to the skin with tweezers (or while wearing gloves). Don’t rub the area; that can activate more stings. An ice pack can sometimes help reduce discomfort. If the person stung seems to be showing any signs of a serious allergic reaction (difficulty breathing, altered state of consciousness) seek emergency medical attention immediately.
You will probably notice sea urchins when snorkeling. Sea urchins, which first appeared on Earth about 500 million years ago, look really cool, but are a bit like little living pincushions. They have long spines, which are used to help move the sea urchin from place to place, to capture food, and to protect the sea urchin from harm. If you step on a sea urchin or grab one by accident while snorkeling, you’ll wish you hadn’t. So be careful where you step or sit when in the water.
If you get punctured by a sea urchin, try to remove as much of the spine as possible with tweezers, and soak the injured area in hot water for 30 to 60 minutes. Carefully dry the wound and apply antibiotic ointment. If it’s a particular bad puncture, appears to be infected, or isn’t healing well, see doctor.
Many people like to collect shells. However, as you know, shells are created by little creatures to serve as their portable home, and many of these creatures have a proboscis (a long stinger) which they used to disable and capture prey. It can also sting you. The proboscis can inject a venom containing a neurotoxin, which causes pain, swelling, and numbness, into curious folks who try to pick them up. Shells washed up on the beach have generally been vacated by their former owners, so they may be fine to pick up, but use caution with any shells in the ocean; the original owner may still be present. The recommended treatment, should you get stung while handling a shell, is to soak the affected area in hot water.
You are not likely to see a shark on your trip, but if you do encounter one, SWIM AWAY SLOWLY. Slow, calm movements will avoid drawing their attention. If you thrash about in fear trying to hurry away, that will get you noticed. The shark may then mistake you for a fish in distress and decide you’d make a good meal.