Other fossils show that corals may have been present shortly before 490 million years ago and diversified a few million years later. Cnidarian, any member of the phylum cnidaria (coelenterata), a group of more than 9,000 species of mostly marine animals Cnidarians are diploblastic organisms, with their body cells organized in two distinct germinal layers, the ectoderm and endoderm The phylum cnidaria includes such diverse forms as jellyfish, hydra, sea anemones, and corals Cnidarians are radially or biradially symmetric, a general type of symmetry believed primitive for eumetazoans. Cnidarians are found in many aquatic environments.
Phylum cnidaria includes animals that show radial or biradial symmetry and are diploblastic They develop from two embryonic layers Nearly all (about 99 percent) cnidarians are marine species. Cnidarians are a diverse group of animals that belong to the phylum cnidaria They are characterized by the presence of specialized stinging cells called cnidocytes, which are used for defense and capturing prey Cnidarians exhibit a wide range of body forms, including polyps, medusae, and colonies.
These organisms are found in both marine and freshwater environments. Cnidaria (pronounced with a silent c) is a phylum containing some 11,000 species of relatively simple invertebrate animals found exclusively in aquatic, mostly marine, environments. Cnidarians are a diverse group of marine animals that belong to the phylum cnidaria
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