Phylum Coelenterata (Cnidaria)

Explanation

(i) Body of coelenterates is cylindrical called 'polyp' or umbrella-like called 'Medusa'.
(ii) Most of them are marine, only few are fresh-water dwellers.
(iii) Body is radially symmetrical and diploblastic
(iv) Cnidoblast bearing tentacles are present around mouth. Tentacles are useful for capturing the prey, whereas cnidoblasts inject the toxin in the body of prey. These are useful for protection too. e.g. Hydra, Adamsia, (Sea anemone), Physalia (Portugese-man-of war), Aurelia· (Jellyfish), Corals, etc.