The specific term now used by biologists to describe members of a Phylum which are principally marine animals, radially symmetrical, and which have tentacles (i.e. jellyfish). Reproduction usually encompasses a polyp and/or medusa stage. Previously this Phylum was aggregated with others under the term coelenterates.
Animals having no spine. This group originally contained Spongiaria, Cnidaria and Ctenophora. Coelenterata is a term which generally includes the cnidarians and ctenophores. As the phylum Cnidaria does not include the ctenophores, the two terms are not interchangeable.... coelenterates
The stinging cells present on the tentacles (and the bell of some species) of cnidarian. Each nematocyst consists of an coiled tube which may be bathed in venom. When the trigger on the outside of the nematocyst is touched, the tube rapidly inverts itself firing rather like a harpoon into the tissues of the prey. Venom on the outside of this tube is thus deposited in the tissues, and possibly into blood vessels during this trajectory. Finally, in some specialised nematocysts venom is then discharged through the open end of this thread tube and is deposited in the tissues o f the prey.... nematocyst
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