He lives with fish, but the jellyfish isn't a fish at all. This animal has no blood, brain, spine, heart or gills, but he has stinging cells on his tentacles and other body parts. He may jiggle like jelly, but this guy is mostly water. Florida has several different species of jellyfish.
Hold the Jelly
Jellyfish are invertebrates, members of taxonomic phylum Cnidaria, which includes corals and sea anemones. The outer layer is the epidermis; the middle layer is the "jelly" part, mesoglea; the inner layer is the gastrodermis. Lacking a brain, this animal has an elementary nervous system with receptors to detect light, odor and other stimuli, as well as to respond to the environment. Jellyfish have tentacles extending from their bodies, which can be quite irritating if you come in contact with the right -- or wrong -- jellyfish. Nematocysts, or stinging cells, are located on the tentacles and inject venom or toxins into prey.
Found throughout the world, the moon jellyfish inhabits coastal Florida. This fellow is about 7 inches in diameter and doesn't carry much of a bite to his sting. The cannonball jellyfish inhabits the Gulf of Mexico and the southeastern coast of Florida. He can get to 10 inches in diameter and has eight "arms" extending from his mouth to help him move and catch prey. The cannonball usually has a mild sting and is edible; in fact, some cultures consider this creature to be a delicacy. The blue button is small and sports a pretty blue color with a bluish-purple fringe. He's found in the panhandle region and on the Atlantic coast of Florida and doesn't carry much of a punch.
If you encounter a sea nettle, you'll likely know it, as he has a harsh sting. This guy's color changes according to the salinity of the water he's in. In low-salinity water, he's white; he'll have reddish markings if he's in an area with a higher salt content. His tentacles are long and flowing, so it's easy to get stung by him if you're out for a swim. The mauve stinger jellyfish, about 4 inches in diameter, is another jellyfish who packs a potent punch with his sting.
Potentially Dangerous Stingers
Several varieties of box jellyfish live in Florida's waters. Their stings are rare, but they have dangerous consequences, the National Science Foundation notes. Irukandji syndrome has occurred from this guy's touch. Irukandji syndrome is a group of "agonizing" symptoms, says the NSF, including heart failure, from the creature's venom; the syndrome is responsible for at least two deaths in Australia.
The Portuguese man-of-war isn't a jellyfish but is a siphonophore, which has several different organisms living and functioning together in a marine environment. This guy is associated with jellyfish, however, because he stings -- severely. The man of war is distinctive with its balloonlike float that is purplish-blue in color, sailing along the water. The tentacles can be longer than 30 feet, giving the creature an especially extensive reach for stinging. The venom isn't usually deadly; however, the Portuguese man-of-war's painful sting warrants a trip to the doctor to ward against serious side effects.
Jelly Without Sting
You may come across a few other jellyfish in Florida. The by-the-wind sailor jellyfish resembles a little sailboat. This pretty little jelly reaches about 3 inches long and is found in warm waters worldwide, including Florida's Atlantic coast. The mushroom, or mushroom cap, jellyfish is named for a creamy white or translucent bell.
- Jelly Watch: Fun Facts About Jellyfish
- BeachHunter.net: Jellyfish in Florida - Jellyfish Identification
- Florida Department of Environmental Protection: Northwest District Envirofact Northwest District - Envirofact/Jellyfish and Sea Nettles
- National Science Foundation: Jellyfish Gone Wild: Sting
- National Oceanic and Atmospheric Association: Jellyfish
- National Science Foundation: Jellyfish Gone Wild: Gulf Coast
- Monterey Bay Aquarium: By-the-Wind Sailor
- Encyclopedia of Life: Pelagia noctiluca; Mauve Stinger
- Applachian State University Jelly Stalkers: Rhopilema Verrilli
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