The ocean is their stage. Jumping, gliding, and rolling through the water, jellyfish are graceful and amazing creatures. Many jellyfish use their bell (the umbrella-like part) to propel themselves through the water by contracting it. Some have no propulsion but allow the water to carry them along. Comb jellyfish are bioluminescent. They glow as they rotate through the ocean. Jellyfish are approximately 96% water, 3% salts, and 1% organic material. How can such a fragile animal survive?
The body of a jellyfish typically has three layers of tissue. The outer layer provides protection, the middle layer is a thick elastic material, and the innermost layer is a type of "gut", digesting food. This "gut" acts as gullet, stomach, and intestine. Jellyfish have no heart, brain, liver, or kidneys. Instead of a brain, they have something called a "nerve net". It is made up of receptors that pick up light, odors, and other things. The "nerve net" tells the rest of the jellyfish's body how to respond. There is one opening for intake of food and release of waste. Four to eight arms, which act as a mouth, receive food from the tentacles. Jellyfish eat zooplankton such as krill, larval fish, larvae, and gelatinous animals.
The tentacles on some jellyfish contain nematocysts. These small stingers are triggered by touch. When something brushes up against a tentacle, that object gets stung by the tentacle of the jellyfish. This stuns the object so that the jellyfish can grab it and move it into one of the "mouth" arms, and then into the intake opening. There are over 250 types of jellyfish, from the very small Umbrella jellyfish to the larger Portuguese Man-of-War. The sting from the smaller jellyfish is unpleasant but not life threatening. The Man-of-War's sting is deadly.
The Portuguese Man-of-War's tentacles can extend up to 65 feet. A swimmer in the tropics doesn't have to be very close to a Man-of-War to get stung. If you are stung, get out of the water immediately. Remove the tentacles gently so they won't sting again. The tentacles stay in the skin like bee stings do, and continue to pump toxin into the skin. Many lifeguards use meat tenderizer on the sting. The meat tenderizer breaks down the toxin. Get to a hospital right away. Symptoms of Man-of-War stings include pain, shock, and fainting..
Other jellyfish stings are milder, from prickly sensations to a mild burning feeling in the area stung. To relieve the pain, rinse the area with sea water and pour on some vinegar if it's handy. Apply talcum powder or shave cream and scrape it off
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