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