Introduction to Animals

1. Introduction to Animals

2. Characteristics • Multicellular Organization • Heterotrophic • Sexual reproduction and development • Movement

3. Multicellular Organization • Most animals contain large numbers of cells. • Humans contain 50 trillion cells. • In most animals, there is a division of labor. • Specialization is the adaptation of a cell for a particular function. • Tissues are the organization of cells. Cell are able to organize by the joining of cells by cell junctions. • Cell specialization has allowed organisms to evolve and adapt to many environments.

4. Animals are Heterotrophic • They must obtain complex organic material from other sources. • Most accomplish this through ingestion. • Digestion is accomplished within the animal. This process extracts the carbohydrates, protein and lipids from the food eaten.

5. Sexual Reproduction and Development • Sexual reproduction restores the diploid number and increases genetic variation. • During the developmental process, the zygote undergoes many mitotic divisions. These identical cells must undergo differentiation. • Differentiation is process of cell becoming different from each other and being specialized.

6. Movement • Most animal are able to move. • The ability to move results from the interrelations of two types of tissues found only in animals: nervous tissue and muscular tissue. • There are a few animals that are sessile.

7. Origin and Classification • The first animals probably arose from the sea. • Taxonomists have grouped animals into several phyla based on evolutionary relationships. • Many taxonomist recognize 30 or more animal phyla. We will investigate 11 phyla. Ten of the phyla include invertebrates and only Chordata includes the vertebrates.

8. Animal Body Structure • Symmetry • Germ layers • Body Cavities

9. Symmetry • Symmetry refers to the consistent overall pattern of structure of an animal. • Animals have three patterns of symmetry. • Asymmetry – no symmetry • Radial Symmetry – similar parts branch in all directions from a central point • Bilateral Symmetry- similar halves on either side of a central plane.

10. Patterns of Symmetry

11. Identify the Type of Symmetry

12. Most animals have a dorsal, ventral, anterior and posterior side or orientation. • Dorsal – top • Ventral – bottom • Anterior – head • Posterior - tail • Most animals exhibit cephalization, the concentration of sensory and brain structures in the anterior. Animals with cephalization have a head!

13. Germ Layers • Germ layers are fundamental tissue types found in all animals except sponges (no true tissues). • Ectoderm • Mesoderm • Endoderm

14. Body Cavities • Most animals have a fluid filled space that forms between the digestive tract and the outer wall of the body during development. This space is known as a COELOM.

15. Acoelomate (without a coelom) • 2 germ layers • ectoderm and endoderm • not separated by a cavity • least complex body plan • sponges and cnidarians • 3 layer acoelomate • 3 germ layers • endoderm, mesoderm and ectoderm • not separated by a cavity • flatworms • Pseudocoelomate • pseudocoelom • cavity formed between mesoderm and endoderm • roundworms and rotifers • Coelomate • cavity developed within the mesoderm • most complex body plan • mollusks, annelids, arthropods, echinoderms, and chordates

16. Animal Diversity • Invertebrates • 10 phyla • 95% of animals • Chordates • Notochord • Dorsal nerve cord • Pharyngeal pouches • Postanal tail • Vertebrates • Include fishes, birds and mammals

17. What is the difference in a vertebrate and an invertebrate? A vertebrate is an animal with a backbone and invertebrates do not have a backbone.

18. Comparison of Invertebrates and Vertebrates • Vocabulary