Diploblasty is a condition of theblastula in which there are two primarygerm layers: theectoderm andendoderm.[1]
Diploblastic organisms are organisms which develop from such a blastula, and includeCnidaria andCtenophora, formerly grouped together in the phylum Coelenterata, but later understanding of their differences resulted in their being placed in separate phyla.
The endoderm allows them to develop truetissue. This includes tissue associated with the gut and associated glands. The ectoderm, on the other hand, gives rise to the epidermis, the nervous tissue, and if present, nephridia.
Simpler animals, such assea sponges, have one germ layer and lack true tissue organization.
All the more complex animals (from flat worms to humans) aretriploblastic with three germ layers (amesoderm as well as ectoderm and endoderm). The mesoderm allows them to develop trueorgans.
Groups of diploblastic animals alive today include jellyfish, corals, sea anemones and comb jellies.
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