Before the development of molecular techniques, scientists classified animals based on shared morphological and embryological characters. Complete the sentences discussing the bases for traditional animal classification. Animals possess specialized ____________ . The division of animals as radial or bilateral is based on each group's body ____________ . The Bilateria are, in turn, divided into three major classifications based upon the structure of the ____________ . This feature is important because it allows for organs to be cushioned by ____________ that is relatively incompressible. Lastly, animals can be classified by the way their zygotes subsequently divide to form a multicellular individual; the embryological pathway can proceed by either ____________ cleavage. cartilage complete or incomplete fluid mitotic or meiotic nucleic acids organs radial or spiral tissues symmetry DNA BODY CAVITY FLUID BONE
