Jellyfish General Knowledge Facts

Chironex fleckeri is the scientific name of jellyfish. Jelly fish are typified as free-swimming marine animals consisting of a gelatinous tortoise-shaped bell and trailing. Jellyfish are found in every ocean, from the surface to the deep sea. A few jellyfish inhabit freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. The English popular name jellyfish has been in use since 1796. It has traditionally also been applied to other animals sharing a superficial resemblance. Even some scientists include the phylum ctenophora when they are referring to jellyfish. The Jellyfish body consist of over 95% water. Most of their umbrella mass is a gelatinous material—the jelly—called mesoglea which is surrounded by two layers of protective skin. As jellyfish are not even vertebrates, let alone true fish, the usual word jellyfish is considered by some to be a misnomer, and American public aquariums have popularized use of the terms jellies or sea jellies instead. A group of jellyfish is sometimes called a bloom or a swarm.  "Bloom" is usually used for a large group of jellyfish that gather in a small area, but may also have a time component, referring to seasonal increases, or numbers beyond what was expected. Using "swarm" usually implies some kind of active ability to stay together, which a few species such as Aurelia, the moon jelly, demonstrate. The lion's mane jellyfish is the largest known species of jellyfish. Its range is confined to cold, boreal waters of the Arctic, northern Atlantic, and northern Pacific Oceans. The smallest jellyfish are the peculiar creeping jellyfish in the genera Staurocladia and Eleutheria, which have bell disks from 0.5 mm to a few mm diameter. Jellyfish range from about one millimeter in bell height and diameter to nearly two meters in bell height and diameter; the tentacles and mouth parts usually extend beyond this bell dimension. Comb jellyfish is, is not a jellyfish at all. Because Jellyfish as a species belong to the phylum, Cnidaria, Whereas, comb jellies are an entire separate phylum themselves called Ctenophore. Jellyfish has been around for more than 650 million years which means that they outdate both dinosaurs and sharks. The worlds largest known jellyfish can reach a diameter of 2.5 m and its tentacles can grow to be half the length of a football field.  Jellyfish are symmetrical about a central axis that runs through the length of their body, from the top of their bell to the ends of their tentacles.  A jellyfish takes food in through its mouth which is located on the underside if its bell. Food is digested in a sac-like structure called a coelenteron or gastrovascular cavity. Waste material is passed out through the mouth. A jellyfishes' body consists of three layers. The outer layer is called the epidermis, the inner layer which lines the gastrovascular cavity is called the gastrodermis, and the middle layer consists of a thick substance called the mesoglea. Jellyfishes have no brain, no blood, and no nervous system. Their senses are primitive and consist of a neural net, eye spots that can sense light from dark, and chemosensory pits that help them identify potential prey. True Jellyfish are species belonging to the Class Scyphozoa. Examples of True Jellyfish include Moon Jellies, Mediterranean Jellyfish, Sea Nettles, Lion's Mane Jellyfish, Blue Jellies, and many other lesser known species.