Chapter 24 Introduction to Animals

2. Chapter 24 Introduction to Animals Section 1: Animal Characteristics Section2: Animal Body Plans Section 3: Sponges and Cnidarians

3. Introduction to Animals Chapter 24 24.1 Animal Characteristics • The ancestral animals at the beginning of the evolutionary tree are eukaryotic and multicellular. • They developed adaptations in structure that enabled them to function in numerous habitats. General Animal Features

4. Introduction to Animals Chapter 24 24.1 Animal Characteristics Feeding and Digestion • Animals are heterotrophic. • The structure or form of an animal’s mouth parts determines how its mouth functions.

5. Introduction to Animals Chapter 24 24.1 Animal Characteristics Support • Invertebrates • Any animal without a backbone. • 95-99% of animal species are invertebrates • The bodies of most are covered by exoskeletons.

6. Introduction to Animals Chapter 24 24.1 Animal Characteristics Support • Exoskeletons • Hard or tough outer coverings that provide a framework of support • Protect soft body tissues • Provide protection from predators

7. Introduction to Animals Chapter 24 24.1 Animal Characteristics Support • Vertebrates • Have an endoskeleton and a backbone

8. Introduction to Animals Chapter 24 24.1 Animal Characteristics Support • Endoskeletons • Protect internal organs • Provide support for the body • Provide an internal brace for muscles to pull against

9. Introduction to Animals Chapter 24 24.1 Animal Characteristics • The evolution of nerve and muscle tissues enables animals to move in ways that are more complex and faster than organisms in other kingdoms. Movement

10. Introduction to Animals Chapter 24 24.1 Animal Characteristics • Most animals reproduce sexually, although some can reproduce asexually. • Some animals, such as earthworms, are hermaphrodites, producing eggs and sperm in the same body. Reproduction

11. Introduction to Animals Chapter 24 24.1 Animal Characteristics • Fertilization occurs when the sperm penetrates the egg to form a fertilized egg cell called the zygote. • Fertilization can be 1) internal or 2) external Sexual Reproduction

12. Introduction to Animals Chapter 24 24.1 Animal Characteristics • Internal fertilization • The sperm and egg combine in the animal’s body. • External fertilization • Occurs when egg and sperm combine outside the body. • Requires an aquatic environment.

13. Introduction to Animals Chapter 24 24.1 Animal Characteristics • Asexual reproduction means that a single parent produces offspring that are genetically identical to itself. • Budding • Fragmentation • Regeneration • Parthenogenesis

14. Introduction to Animals Chapter 24 24.1 Animal Characteristics • Budding-Offspring develop as a growth on the body of the parent

15. Introduction to Animals Chapter 24 24.1 Animal Characteristics • Fragmentation – Parent breaks into pieces and each piece can develop into an adult organism.

16. Introduction to Animals Chapter 24 24.1 Animal Characteristics • Regeneration – A new organism can regenerate or regrow from the lost body part if the part contains enough genetic information.

17. Introduction to Animals Chapter 24 24.1 Animal Characteristics • Parthenogenesis – A female animal produces eggs that can develop without being fertilized.

18. Introduction to Animals Chapter 24 24.1 Animal Characteristics • The zygote undergoes mitosis and a series of cell divisions to form new cells. • The cells continue to divide, forming a fluid-filled ball of cells called the blastula. Early Development

19. Introduction to Animals Chapter 24 24.1 Animal Characteristics Early Development • The blastula continues to undergo cell division as some cells move inward to form a gastrula.

20. Introduction to Animals Chapter 24 24.1 Animal Characteristics

21. Introduction to Animals Chapter 24

22. Introduction to Animals Chapter 24 24.1 Animal Characteristics Tissue Development • Endoderm • inner layer of cells in the gastrula • Forms the digestive organs and digestive tract lining.

23. Introduction to Animals Chapter 24 24.1 Animal Characteristics Tissue Development • Ectoderm • outer layer of cells in the gastrula • Forms the nervous tissue and skin.

24. Introduction to Animals Chapter 24 24.1 Animal Characteristics • Mesoderm • layer of cells between the endoderm and ectoderm • Forms muscle tissue, circulatory, excretory, and respiratory systems Tissue Development

25. Introduction to Animals Chapter 24 24.1 Animal Characteristics

26. Introduction to Animals Chapter 24 Animation • Cell Differentiation in Animal Development • Visualizing Protostome and Deuterostome Development • A Sponge • A Cnidarian

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