where is the mouth of a cnidarian located
Cnidaria
Cnidaria ( / naɪˈdɛəriə / ) is a phylum containing over 10,000 species of animals found exclusively in aquatic ( freshwater and marine ) environments : they are predominantly marine species . Their distinguishing feature is cnidocytes , specialized cells that they use mainly for capturing prey . Their bodies consist of mesoglea , a non-living jelly - like substance , sandwiched between two layers of epithelium that are mostly one cell thick . They have two basic body forms : swimming medusae and sessile polyps , both of which are radially symmetrical with mouths surrounded by tentacles that bear cnidocytes . Both forms have a single orifice and body cavity that are used for digestion and respiration . Many cnidarian species produce colonies that are single organisms composed of medusa - like or polyp - like zooids , or both ( hence they are trimorphic ) . Cnidarians ' activities are coordinated by a decentralized nerve net and simple receptors . Several free - swimming species of Cubozoa and Scyphozoa possess balance - sensing statocysts , and some have simple eyes . Not all cnidarians reproduce sexually , with many species having complex life cycles of asexual polyp stages and sexual medusae . Some , however , omit either the polyp or the medusa stage . 
Cnidaria ( / naɪˈdɛəriə / ) is a phylum containing over 10,000 species of animals found exclusively in aquatic ( freshwater and marine ) environments : they are predominantly marine species . Their distinguishing feature is cnidocytes , specialized cells that they use mainly for capturing prey . Their bodies consist of mesoglea , a non-living jelly - like substance , sandwiched between two layers of epithelium that are mostly one cell thick . They have two basic body forms : swimming medusae and sessile polyps , both of which are radially symmetrical with mouths surrounded by tentacles that bear cnidocytes . Both forms have a single orifice and body cavity that are used for digestion and respiration . Many cnidarian species produce colonies that are single organisms composed of medusa - like or polyp - like zooids , or both ( hence they are trimorphic ) . Cnidarians ' activities are coordinated by a decentralized nerve net and simple receptors . Several free - swimming species of Cubozoa and Scyphozoa possess balance - sensing statocysts , and some have simple eyes . Not all cnidarians reproduce sexually , with many species having complex life cycles of asexual polyp stages and sexual medusae . Some , however , omit either the polyp or the medusa stage .
The mouths are surrounded by tentacles that bear cnidocytes.
Their distinguishing feature is cnidocytes , specialized cells that they use mainly for capturing prey . They have two basic body forms : swimming medusae and sessile polyps , both of which are radially symmetrical with mouths surrounded by tentacles that bear cnidocytes .