Triploblastic animals have an ectoderm, mesoderm, and endoderm; as well as a bilateral symmetry. Triploblastic describes an animal having a body composed of three embryonic cell layers; the ectoderm, mesoderm, and endoderm. Most multicellular animals are triploblastic; the coelenterates which are diploblastic are an exception. A diploblastic animal possess two major tissue layer that is the outer layer (ectoderm) and the inner layer (endoderm).
