Animal_Lecture jocelyns dont delete

Animal_Lecture jocelyns dont delete - Animal Lecture...

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Animal Lecture Lecture Objectives chapter 32 1.3 million known species 10-200 million not discovered Morphology- an external characteristic or physical trait. General Characteristics of Animals Shared characteristics Heterotroph - an organism that can’t make their own food. Eats other animals. All animals have multiple cells Lack cell wall Most animals can move (muscle tissue + nerve tissue= movement) Diverse in form and habitat Most reproduce sexually (some exceptions) Have a characteristic pattern of embryonic development o Hox genes control patterns of development Cells are organized into tissues (except in sponges) Review at 32.1 in text. Spiralia Sponges, Cnidaria, Acoela, Platyzoa, Lophotrochozoa, Ecdysozoa, Deuterostomia Fig 32.4 Animals evolved from a colonial Choanoflagellate ancestor o Choanoflagellate Single-celled organisms, tiny, and have flagella. Metazoa- includes all animals in the animal kingdom o Parazoa- includes sponges. (near animal) o Eumetazoa- includes everybody else. (true animal)
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Bilateria- Bilateral organisms are in this group. Key evolutionary transitions in animal evolution (body plan) 1. Tissues 2. Symmetry 3. Body cavity 4. Development 5. Segmentation Key Evolutionary Transition: 1) tissues Parazoa (sponges) o No defined tissues and organs o Cells have reversible roles (e.g., a single sponge cell can regenerate into a new sponge) Eumetazoa (all other animals) o Have distinct and well-defined tissues o Have irreversible differentiation of most cell types (e.g., a nerve cell is always a nerve cell) Key Evolutionary transitions: 2) Symmetry Parazoa o Sponges lack any definite symmetry (asymmetrical) Eumetazoa o Eumetazoa have symmetry defined along an imaginary axis drawn through the animal’s body Two main types: Radial symmetry Bilateral Symmetry Radial symmetry Body parts arranged around central axis (fig. 32.1a)
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Can be bisected into two equal halves in any 2-D plane Bilateral Symmetry Body has right and left halves that are mirror images (fig. 32.1b) Only sagittal plane bisects the animal into two equal halves Advantages of Bilateral Symmetry over Radial Symmetry 1. Cephalization a. Evolution of a definite bran area. 2. Greater mobility Key Evolutionary Transistions 3) Body Cavity Eumetazoa produce three germ layers ( Triploblastic ) o Germ layers- layers of cells that will turn into tissues. 1 st layer- Outer ectoderm (body coverings and nervous system) 2 nd layer- Middle mesoderm (skeleton and muscles) 3 rd layer- Inner endoderm (digestive organs and intestines) Body cavity= space surrounded by mesoderm tissue that is formed during development.
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Animal_Lecture jocelyns dont delete - Animal Lecture...

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