BIO153H5 Chapter Notes - Chapter 32: Protostome, The Animal Kingdom, Body Cavity
Document Summary
Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers: there are exceptions to nearly every criterion for distinguishing animals from other life- forms. Paleozoic era (542 251 million years ago: the cambrian explosion (535 to 525 million years ago) marks the earliest fossil appearance of many major groups of living animals, there are several hypotheses regarding the cause of the cambrian explosion. The evolution of the hox gene complex. Some animals have radial symmetry: animals can be categorized according to the symmetry of their bodies, or lack of it, two-sided symmetry is called bilateral symmetry, animals with bilateral symmetry have: A dorsal (top) side and a ventral (bottom) side. Cephalization, the development of a head. (brain ) Body cavities most triploblastic animals possess a body cavity: a true body cavity is called a coelom and is derived from mesoderm.
