Characteristics

• A diploblastic metazoan. Has an endoderm and ectoderm that is seperated by acellular mesoglea or cellular mesenchyme that is ectoderm in origin.
• Has radial symmetry with a oral-aborl body axis.
• Has stinging or adhesive "cnidae" that are produced by cnidocytes. They are normally called nematocysts, spirocysts, and ptychocysts.
• Musculature is made of myoepitheilial cells that are ecto/endoderm of origin.
• Has an alternation in reproduction: Asexual polypoid and sexual medusoid generations. (varries with species)
• Has only one gastrovascular body cavity called the coeleteron that is entodermally derived.
• Single opening that is both the mouth and anus.
• No head or central nervous system but has nerve nets that are large, naked nonpolar neurons.
• Planula larvae that are ciliated and motile.