“Cnidarians” is Greek for “nettle” (“Introduction to Cnidarians”). The phylum Cnidaria includes freshwater hydras, jellyfish and corals. Each of these invertebrates goes through transitions in body forms. Jellyfish are the most unusual and complex of the phylum. Jellyfish belong to the class Jellyfish, which means true jellyfish. Cnidarians are found in the Mediterranean and oceans. They can live in the ocean as well as coastal waters. But the main habitat of Cnidarians is in the open ocean. Jellyfish can live in any ocean. There are deep and shallow water jellyfish, like the Pelagia Noctiluca, that can live wherever ocean currents decide to carry them. Phyla Cnidaria, Platyhelminthes and Nematoda"). A jellyfish's unique body structure helps it move, feed and protect itself. Their body is known as a bell. During the bell stage, jellyfish , the jellyfish is mobile and is specialized for swimming But in some Cnidarians, the bell stage only appears in the embryonic stage ("Phyla Cnidaria, Platyhelminthes and Nematoda"). polyp (vase stage) which is a sessile (or immobile) life Jellyfish have neither back nor front, neither left nor right. They have neither heart, nor head, nor legs, nor fins (Zimmer). They have a stomach pouch to hold food, the bell (body), oral arms that bring captured food to the mouth, tentacles that sting and kill prey, a mouth connected to digestive structures to digest food, and gonads which are reproductive organs Jellyfish are also 95% water (Northeaster University). Jellyfish move by expanding and contracting to push water behind them. Between each contraction and expansion, there is a pause so that a vortex can be created...... middle of paper ...... Jellyfish do not have an excretory system, hence the hole for the mouth also serves as the anus (“Pelagia Noctiluca”). A jellyfish does not have a circulatory system because it is radially symmetrical, meaning it has a symmetrical arrangement of its parts around a central point. (“Pelagia Noctiluca”) Jellyfish are a unique and interesting species. Even though jellyfish look complex, they are simple. They have very few internal systems, such as the respiratory, circulatory, excretory, and nervous systems. Even though they do not have a nervous system, they have the ability to sting and kill their prey to survive. Chemicals can make them shine. They can move by expansions and contractions. They can reproduce asexually and sexually. They are simple invertebrates but nevertheless remain unique and interesting. Jellyfish are fascinating and more complex than they seem.