List of cnidarians of Ireland

[1] The cnidarians' 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).