Every year, hundreds of thousands of jellyfish pass through our waters.
Most jellyfish along the South Carolina coast are harmless, but in the months of August and September we get some warm water visitors that can ruin a perfect beach day. Sea Nettles are the most common stinging jellies found in our late summer waters.
Jellyfish are brainless and generally free-floating creatures.
They have a rudimentary nervous system with receptors that detect sunlight, odors and other stimuli. Jellyfish have radial symmetry. This means that all of their body parts radiate from a single axis. This genetic design allows them to respond to stimuli from any direction.
These animals rely on ocean currents, tides and winds as their main transportation. At the same time, they are able to swim in a vertical motion. Jellyfish contract their bell-shaped heads to move up and down in the water column as they search for food or move towards sunlight. Although many people may think that jellyfish attack on purpose, these animals react reflexively to contact and do not intend to cause humans any harm.
The outer layer of a jellyfish bell is called the epidermis.
The inner layer of the bell that lines their gut is referred to as the gastrodermi. The interior of a jellyfish houses its digestive cavity and simple nervous system. This inner area, called the coelenterons, contains the jellyfish’s gullet, stomach and intestines. These animals have one opening that is used for both the input of nutrients as well as their excretions.
They typically have four to eight tentacles that dangle below the bell and transport food from the tentacles to the mouth. These tentacles are coated with cnidocytes, venom-filled capsules with tiny barbs that inject toxins into prey, immobilizing them. Jellyfish are carnivores eating zooplankton, other jellyfish, small fish and even crustaceans.
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Sea nettle stings are not pleasant.
Their tentacles contain both a trigger and a stinging structure. While floating through our waters, their tentacles will come into contact with something solid, which stimulates the trigger releasing tiny barbs full of toxin. The severity of a sting will depend on a number of factors: the thickness of the skin in contact, the penetrating power of the barbs and the sensitivity of the victim to the toxins. Jellyfish stings can usually be treated at home; however facial or genital stings should be treated by a doctor.
If stung by a jellyfish, the first thing to do is remove the barbs. Barbs that are not removed will continue to release toxins into the body. Sand, towels, clothing or any available rough material will help in removing these barbs. Beach Patrol members on duty are equipped with spray bottles full of white vinegar, which helps neutralize the toxins. Baking soda may also be used. The notion that urine will help aid a jellyfish sting is a myth; in fact, urine may stimulate the barbs to fire more toxins. Once the toxins have been neutralized, using topical Benadryl or calamine lotion will ease the itch that follows a sting.
Tentacles can sting whether they are attached to the jellyfish’s body or not.
Tentacles and pieces of tentacles can wash up with sea grasses and other ocean debris onto the beaches, so take caution during the heavy jellyfish season.
The best way to avoid Sea Nettle stings would be to avoid entering the water during migrating season. However, for those of us who can’t stay out of the ocean, wearing wetsuits or rash guards or even panty hose in the water will help to prevent jellyfish stings.
The H2O Nature Center, which features live reptile and amphibian exhibits and hands-on displays, focuses on the wildlife and habitats of the South Carolina Lowcountry. Nature tours, apparel, gifts, books and bicycle/fishing gear rentals are also available. To reserve a tour, call 843-686-5323 or visit www.h2osportsonline.com.
By Kathleen McMenamin, Master Naturalist