Differentiate between a diplobastic and a triploblastic animal.
Animals in which the cells are arranged in two embryonic layers, an external ectoderm and an internal endoderm are called diplobastic animals (e.g., coelentrates). While those animals in which the developing embryo has a third germinal layer, i.e., mesoderm lying between the ectoderm and endoderm are called triploblastic animals. (e.g., chordates.)