Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are anchored to the seabed by stalks rather than being mobile. The bell can pulsate to provide propulsion for highly efficient locomotion. The tentacles are armed with stinging cells and may be used to capture prey and defend against predators. Jellyfish have a complex life cycle; the medusa is normally the sexual phase, which produces planula larva that disperse widely and enter a sedentary polyp phase before reaching sexual maturity.
Kingdom : Animalia
Phylum : Cnidaria
Subphylum : Medusozoa
*some Hydrozoa—small jellyfish
Cladistically included but traditionally excluded taxa
* some Hydrozoa, such as Hydra
Jellyfish are found all over the world, from surface waters to the deep sea. Scyphozoans (the “true jellyfish”) are exclusively marine, but some hydrozoans with a similar appearance live in freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. The medusae of most species are fast-growing, and mature within a few months then die soon after breeding, but the polyp stage, attached to the seabed, may be much more long-lived. Jellyfish have been in existence for at least 500 million years,and possibly 700 million years or more, making them the oldest multi-organ animal group.
Jellyfish are eaten by humans in certain cultures. They are considered a delicacy in some Asian countries, where species in the Rhizostomae order are pressed and salted to remove excess water. Australian researchers have described them as a “perfect food”, sustainable, and protein-rich but relatively low in food energy.
They are also used in research, where the green fluorescent protein used by some species to cause bioluminescence has been adapted as a fluorescent marker for genes inserted into other cells or organisms.
The stinging cells used by jellyfish to subdue their prey can injure humans. Many thousands of swimmers are stung every year, with effects ranging from mild discomfort to serious injury or even death; small box jellyfish are responsible for many of these deaths. When conditions are favourable, jellyfish can form vast swarms, which can be responsible for damage to fishing gear by filling fishing nets, and sometimes clog the cooling systems of power and desalination plants which draw their water from the sea.
The name jellyfish, in use since 1796, has traditionally been applied to medusae and all similar animals including the comb jellies (ctenophores, another phylum).The term jellies or sea jellies is more recent, having been introduced by public aquaria in an effort to avoid use of the word “fish” with its modern connotation of an animal with a backbone, though shellfish, cuttlefish and starfish are not vertebrates either. In scientific literature, “jelly” and “jellyfish” have been used interchangeably.Many sources refer to only scyphozoans as “true jellyfish”.
A group of jellyfish is called a “smack”.
* Some jellyfish can glow in the dark.
* Jellyfish are the oldest multi-organ animal.
* Jellyfish don’t have brains.
* Jellyfish are found all over the world.
* Some jellyfish are immortal.
* Not all jellyfish have tentacles.
* There’s a giant jellyfish called the hair jelly.
* Jellyfish stings can be deadly.
* 150 million people are stung by jellyfish each year.
* Jellyfish have many predators.
TYPE OF JELLYFISHS
Coming in at number one is the Crystal jellyfish. Located in the waters around North America’s coast, this jellyfish species is actually completely colorless, hence its name! This beautiful specimen has around 150 tentacles lining its glass-like bell and in the daylight looks crystal clear. Although, this transparency belies a brighter side.
2.Bloodybelly Comb Jellyfish
Ranking high in the charts for the coolest and beautiful jelly-fish, is our next contender, the Bloodybelly Comb jellies, which, technically speaking are comb jellies and are only very distantly related to the jellyfish. This one doesn’t have the famous jellyfish stinging tentacles that others possess, and it is actually a harmless Comb jelly to humans.
Red looks very much like black in the depths of the ocean and specifically, the red belly of this Bloodybelly comb also helps to mask the bioluminescence glow of its prey and keeps it extra safe from the attention of its predators.
Getting its name from the wart-like projections this type has on its bell resembling that of a vegetable, we give you the Cauliflower jellyfish also referred to as the Crown jellyfish! While this jelly may not sound the prettiest of its species, it is still a truly beautiful species of jellyfish.
Very much like its vegetable nickname, this kind is often also found on dinner plates! Mostly in China and Japan where the species is considered to be a delicacy and is also known to be used for medicinal purposes within these locations.
4. White-spotted Jellyfish
At number four on, we have the White-spotted jellyfish. These jellies have very mild venom and therefore any jellyfish stings from its stinging cells are harmless to us humans. In fact, the white-spotted jelly doesn’t generally even use their venom to catch food at all!
5. Black Sea Nettle Jellyfish
Next, one of the largest jellyfish (the largest jellyfish is the Lion Mane jellyfish) is the Black Sea Nettles jellyfish! This particular species can be found in the deep sea Pacific waters around Southern California.
The bell of the Black Sea Nettles can reach up to three-foot across, its long tentacles reach up to 20 feet in length, and its stinging tentacles 25 feet long. Without saying, it would be pretty damn scary if you caught yourself in the middle of a bloom of these giants while in the water, but don’t worry too much as they are not that common to a lot of ocean waters.