Jellyfish nervous systems

What are jellyfish? The term jellyfish generally refers to the umbrellashaped gelatinous zooplanktons that belong to Scyphozoa (true jellyfish), Staurozoa (stalked jellyfish), Cubozoa (box jellyfish), and Hydrozoa of Phylum Cnidaria. Their sizes, shapes, and habitats are diverse. Sexually mature jellyfish range from millimeters to meters in diameter, and they can be found almost anywhere in the ocean from the arctic to the tropics and from the deep sea to the shoreline (some even live in freshwater). Despite the substantial variety of their morphologies, some features are shared in common. First, they possess cnidocytes or stinging cells with which they capture prey and protect themselves from predators. Second, they have only one external opening for food intake, waste disposal, and gamete discharge. Third, they are radially symmetric around the single oral/aboral body axis, typically with a symmetry order of four or more.