Essay On Jellyfish

There are unusual creatures that have inhabited our planet for at least 500 million years who spend a portion of their lives as plant-like polyps before transforming into some of the greatest ocean predators, all without having any brain, heart, backbone, eyes, ears or teeth. Cnidaria, otherwise known as jellyfish, are gelatinous animals found at all depths within all oceans around the world, and are some of the oldest animals evolutionarily speaking. Jellyfish are rather simplistic, anatomically speaking. They are diploblastic, meaning that they have a body wall with two cell layers, an external epidermis and an internal gastro dermis, with some amount of mesoglea (non-cellular jelly) between these two layers. Jellies are made up of more than 95% water, however, they do “contain some structural proteins, muscle cells, and nerve cells, forming a kind of internal skeleton” (The Ocean Portal Team). These animals have no need for a stomach,
These receptors give jellies the ability to detect light, pick up vibrations, and allows them to smell and taste even though they have no nose or tongue. The “nerve net” also has a few specialized organs called statocysts that enable jellies to sense if they are facing up or down. Statocysts are located on the outside edge of a jelly’s body and are similar to the bones in the inner ear of humans, which help to maintain balance. When jellies are tilted, small stones within a fluid filled sac brush up against cilia relaying a message indicating which direction they are leaning. Lungs are yet another set of organs missing from the jellies’ anatomy, as are gills. So rather than breathing air, or pulling oxygen from the water through a gill system, jellies absorb the oxygen they need through the ectoderm and