Biology 1225 Chapter Notes - Chapter 15: Amniote, Ectotherm, Filter Feeder
23 Sep 2013
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***exam major trends in evolution include: cephalization (head, symmetry, a coelom (fluid filled cavity between intestines and body wall cushions and protects internal organs, segmentation, animals are multicelled heterotrophs that typically ingest food. Their cells are unwalled: animals reproduce sexually and in many cases asexually. They go through a period of embryonic development and most move about during at least part of their life cycle: ***most animals are invertebrates. 287: the earliest animals were aggregations of cells (multicellular) In later lineages, cell movements produced a middle embryonic layer called a mesoderm. Radial animals have no front or back end. They attach to an underwater surface or drift along, so their food can arrive from any direction: bilateral symmetry all other animals have bilateral symmetry. They have a right and left half with body parts repeated on either side of the body.
