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CHARACTERISTICS OF ANIMALS. Characteristics of Animals 1. Multicellular, eukaryotes 2. Heterotrophs 3. Cells w/out cell walls, many have specialized functions 4. Usually have a method of movement 5. Most reproduce sexually 6. Require oxygen. Describe the Body Plans of Animals
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CHARACTERISTICS OF ANIMALS
Characteristics of Animals • 1. Multicellular, eukaryotes • 2. Heterotrophs • 3. Cells w/out cell walls, many have specialized functions • 4. Usually have a method of movement • 5. Most reproduce sexually • 6. Require oxygen
Describe the Body Plans of Animals 1.Symmetry: balance in body proportions a. Asymmetrical:have irregularly shaped bodies, no symmetry
b. Radial Symmetry- a. Can be divided on any plane & sides are equal. b. Parts radiate around central axis (mouth) c. No head or tail end. d. Advantages: can detect & turn toward prey from any direction. e. Disadvantages: no centralization of a nervous system for aggressive movement & food capture. f. EX: starfish, jellyfish
c. Bilateral Symmetry- a. Can be divided on only one plane & each half is a mirror image of the other. b. Advantage- Cephalization- concentration of nerves to form a brain in the head end. c. EX: most running, crawling, swimming animals
Anatomical Vocabulary • a. Anterior/Cephalic- head end • b. Posterior/Caudal- tail end • c. Ventral- bottom; underneath • d. Dorsal- top; on the back • e. Medial- near middle • f. Lateral- away from middle • g. Oral- mouth side • h. Aboral- away from mouth (anus side) Aboral Oral
a. Ectoderm • becomes nervous system, epidermis of the skin, pituitary, lens of eye b. Mesoderm • becomes muscles, skeleton, notochord, circulatory system, kidney, reproductive system c. Endoderm • becomes lining of digestive tract, liver, pancreas, epithelial lining of lungs, many endocrine glands 3.Body Development • As embryo develops, three germ layers form:
4. Body Cavities a. Acoelomates- no body cavity lined with mesoderm • EX: sponges, cnidarians, & flatworms
b. Pseudocoelomates- partial body cavity lined with mesoderm • “Tube within a tube” body plan • EX: roundworms
c. Coelomates- true body cavity lined with mesoderm • EX: all other animals
Advantages of a body cavity (coelom or pseudocoelom): • Fluid in cavity helps distribute food, wastes, hormones, etc. from one end of animal to the other • Better distribution allows animal to grow larger • A place to put things, like new organs • Hydrostatic skeleton- pressure makes cavity rigid