Introduction to Jellyfish
Jellyfish have drifted along on ocean currents for millions of years, even before dinosaurs lived on the Earth. The jellylike creatures pulse along on ocean currents and are abundant in cold and warm ocean water, in deep water, and along coastlines. Jellyfish have tiny stinging cells in their tentacles to stun or paralyze their prey before they eat them. As jellyfish squirt water from their mouths they are propelled forward. Tentacles hang down from the smooth baglike body and sting their prey. Jellyfish stings can be painful to humans and sometimes very dangerous. But jellyfish don't purposely attack humans. Most stings occur when people accidentally touch a jellyfish, but if the sting is from a dangerous species, it can be deadly. Jellyfish digest their food very quickly. They wouldn't be able to float if they had to carry a large, undigested meal around. They eat fish, shrimp, crabs and tiny plants. Sea turtles enjoy the taste of jellyfish. Some jellyfish are clear, but others are in vibrant colors such as pink, yellow, blue, and purple, and often are luminescent.
Cyanea Lamarckii
The Cyanea Lamarckii, also known as the Blue Jellyfish, varies in color from deep blue to pale white. It can reach almost 2m across. Its long tentacles hanging down from the bell's rim, can reach five meters while being almost invisible. It fishes the sea by swimming actively, letting its tentacles out and drawing them in again to eat the catch. Click for more information.
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Cubozoa
The infamous box jellyfish developed its frighteningly powerful venom to instantly stun or kill prey, like fish and shrimp, so their struggle to escape wouldn’t damage its delicate tentacles. Their venom is considered to be among the most deadly in the world, containing toxins that attack the heart, nervous system, and skin cells. It is so overpoweringly painful, human victims have been known to go into shock and drown or die of heart failure before even reaching shore. Survivors can experience considerable pain for weeks and often have significant scarring where the tentacles made contact.
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Pelagia Noctiluca
The slightly stinging purple jellyfish,Pelagia noctiluca has only few catch tentacles trailing from its bell and five feeding tentacles surrounding its mouth. It can grow 40 cm across. When first discovered, it glowed at night, presumably because it was feeding on sea spark flagellates(Noctiluca scintillans).
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Physalia physalis
Portuguese Man-of-wars are also known as bluebottles for the purple-blue color of their pneumatophores (gas filled float). The long, thin tendrils can extend 165 feet (50 meters) in length below the surface, although 30 feet (10 meters) is more the average. They are covered in venom-filled nematocysts used to paralyze and kill fish and other small creatures. For humans, a man-of-war sting is excruciatingly painful, but rarely deadly. But beware—even dead man-of-wars washed up on shore can deliver a sting.
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