BIOL 1F90 Lecture Notes - Lecture 21: Parthenogenesis, Ventral Nerve Cord, Bivalvia
12 Jan 2016
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Biol 1f90 chapter 30 lecture notes: intro to animal diversity. Most have nerves, muscles, capacity to move at some point in the life cycle. Cells exist in extensive extracellular matrix; unique cell junctions. Most likely ancestor a colonial flagellated protest similar to choanoflagellates. Some are colonial; some cells may have taken on specialized functions. Four main morphological and developmental features used: presence or absence of different tissue types, type of body symmetry, presence or absence of a true body cavity, patterns of embryonic development, tissues organs; porifera , symmetry (bilateria) layers) Metazoa all animals; divided into parazoa (no specialized tissues or sponges); eumetazoa (more than one type of tissue and organs) Bilateria are triploblastic 3 layers; radiata are diploblastic 2 layers. Inner layer endoderm; outer layer ectoderm. Mesoderm 3rd layer in bilateral animals (forms muscles and most other. Eumetazoa are radially symmetrical; (radiata) or bilaterally symmetrical. Bilateral animals have cephalization and dorsal and ventral ends (3 germ.
