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