Introduction to Animals: Characteristics, Habits, and Diversity

1. Introduction to Animals

2. Think of an animal… Did you think of an organism that has fur or a bony skeleton? MOST animals have neither bones nor hair!!! So…what are the characteristics that all animals have in common?

3. Animal Characteristics • Multicellular • Eukaryotic (with no cell walls!) • Heterotrophic

4. Dividing Animals Based on Habitat • Animals that live in the water are AQUATIC • Animals that live on land are TERRESTRIAL

5. Multicellular Organization • Most animals contain large numbers of cells • Humans contain 50 trillion cells! • In most animals, cells are specialized to perform different functions • cells  tissues  organs  organ systems • Cell specialization has allowed organisms to evolve and adapt to many environments

6. Animals are Heterotrophic • Heterotrophs must obtain complex organic material from other sources • The animal eats (ingests) and then digests. • Digestion extracts the carbohydrates, protein and lipids from the food eaten

7. Sexual Reproduction and Development • Sexual reproduction increases genetic variation • During the developmental process, the zygote undergoes many mitotic divisions • These identical cells must differentiate • Differentiation is the process of cell becoming different from each other and specializing

8. Gastrulation: step in development when major tissues (germ layers) begin to develop Endoderm, Mesoderm, Ectoderm

9. Movement • Most animals are able to move • The ability to move results from two types of tissues found only in animals: nervous tissue and muscular tissue • There are a few animals that are sessile • Sponges, corals

10. Origin and Classification • First animals arose from the sea • Taxonomists have grouped animals into several phyla based on evolutionary relationships • 95% of animals are invertebrates! • (We will investigate 9 major phyla. Eight of these phyla include invertebrates and only Phylum Chordata includes the vertebrates)

11. Divisions of Animal Body Structure • Symmetry • Cephalization • Germ layers • Body Cavities

12. Symmetry • Symmetry refers to the consistent overall pattern of structure of an animal • Animals have three patterns of symmetry: • Asymmetry – no symmetry • Examples: Fiddler crabs, Sponges (porifera)

13. Symmetry, Continued • Radial Symmetry – similar parts branch in all directions from a central point • Ex: sea star, anemones • Bilateral Symmetry- similar halves on either side of a central plane • Ex: Butterflies, humans

14. Patterns of Symmetry

15. Most animals have a dorsal, ventral, anterior and posterior side or orientation. • Dorsal – top (topside or back) • Ventral – bottom (underside or belly) • Anterior – head • Posterior – tail

16. Cephalization • Most animals exhibit cephalization • Cephalization: the concentration of sensory and brain structures in the anterior (near the head) • Animals with cephalization have a head!

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

18. 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 body cavity is known as a COELOM

19. Human Body Cavities

20. After Gastrulation • Deuterostome: blastopore becomes the anus • Protostome: blastopore becomes the mouth

21. Animal Diversity • 95% Invertebrates (animals without a backbone) • Phylum Porifera (sponges) • Phylum Cnidaria (jellyfish & corals) • Phylum Platyhelminthes (flatworms) • Phylum Nematoda (roundworms) • Phylum Annelida (segmented worms) • Phylum Mollusca (mollusks) • Phylum Echinodermata (spiny sea creatures) • Phylum Arthropoda (insects & spiders) • 5% Vertebrates (animals with a backbone) • Phylum Chordata (Fishes, birds, reptiles, amphibians and mammals)