Ch. 32
– I. Phylogeny- Evolutionary development of a species based on DNA from organisms and embryology.
• A. Major Branches of the Animal kingdom_.– 1. Subkingdom Parazoa
• a. Phylum Porifera_ ( sponges)
• b. Simple structure separates them from all other animals
– 2. Subkingdom Eumetazoa (true tissues)• a. Radial symmetry (_oral and aboral)
• b. Bilateral symmetry, dorsal (top), ventral(bottom), anterior (front/head), posterior(_rear/tail), right and left.
• 1. Cephalization - Concentration of sensory structures at anterior end.
• A. Development and Body plan– 1. Germ Layers = will form the tissue of
the developing embryo.
» a. All eumetazoa animals develop 2_ germ layers (endo and ecto derm)
» b. Cnidaria is the phylum of jellies develop only 2 layers (endo and ecto derm).
• A. 3 Germ layers of Bilateral animals – 1. Ectoderm
» a. Covers surface» b. Animal covering and
central nervous system– 2. Endoderm
» a. Innermost layer» b. lines the developing gut» c. Lines the digestive tract and
pockets give rise to _liver_ and _lungs__ in vertebrates_.– 3. Mesoderm
» a. between endo and ectoderm» b. Forms muscles and most
organs between digestive tract and outer covering
• A. Body _Cavity_.– 1. Acoelomates= no _cavity between
digestive tract and outer body wall.
» a. Filled with mesoderm
– 2. Pseudocoelomate = fluid filled cavity
» a. Not completely lined with mesoderm
– 3. Coelomate = fluid filled cavity lined with mesoderm
» a. Inner and outer mesoderms connected
• I. Zygote development– A. _Protostome vs. Deuterostome_
» 1. Animals are first classified based on symmetry and germ layers
» a. no symmetry = _sponges» b. radial _symmetry_ = Cnidaria» c. Two layers = Cnidaria» 2. Animals then classified by body cavity» 3. Animals are classified by evolutionary lines of
development– B. Protostomes
» 1. Spiral_cleavage_» 2. Mouth first» 3. determinate
– C. Deuterostomes» 1. Radial cleavage» 2. Anus first» 3. _indeterminate
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