Cnidarians are ordered into four principle gatherings that are:The entirely sessile Anthozoa have ocean anemones, corals, and ocean pens. Swimming Scyphozoa have jellyfishCubozoa have box jamsHydrozoa incorporates all the freshwater cnidarians. Most cnidarians go after creatures going in size from microscopic fish to creatures a few times bigger than themselves, however, many get a lot of their nourishment from dinoflagellates, and a couple is parasites. Many are gone after by different creatures including starfish, ocean slugs, fish, turtles, and surprisingly different cnidarians. Numerous scleractinian corals which structure the primary establishment for coral reefs have polyps that are loaded up with harmonious photograph engineered zooxanthellae. While reef-shaping corals are for the most part limited to warm and shallow marine waters, different cnidarians can be found at incredible profundities, in polar districts, and freshwater.