Chapter 24 Introduction to Animals

2. Chapter 24 Introduction to Animals Section 1: Animal Characteristics Section2: Animal Body Plans

3. Introduction to Animals Chapter 24 24.1 Animal Characteristics Animal Features • The ancestral animals at the beginning of the evolutionary tree are eukaryotic and multicellular.

4. Adaptive Radiation • They developed adaptations in structure that enabled them to function in numerous habitats.

5. 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.

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

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

9. Introduction to Animals Chapter 24 24.1 Animal Characteristics Reproduction • Fertilization occurs when the sperm penetrates the egg to form a fertilized egg cell called the zygote. • Internal fertilization • External fertilization

10. 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

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

12. Introduction to Animals Chapter 24 24.1 Animal Characteristics Cell Differentiation in Animal Development

13. Introduction to Animals Chapter 24 24.1 Animal Characteristics Tissue Development • Endoderm • inner layer of cells in the gastrula • Ectoderm • outer layer of cells in the gastrula • Mesoderm • layer of cells between the endoderm and ectoderm

14. Introduction to Animals Chapter 24 24.1 Animal Characteristics

15. Introduction to Animals Chapter 24 24.2 Animal Body Plans Evolution of Animal Body Plans • Anatomical features in animals’ body plans mark the branching points on the evolutionary tree. • Relationships on this tree are inferred by studying similarities in embryological development and shared anatomical features.

16. Introduction to Animals Chapter 24 24.2 Animal Body Plans

17. Introduction to Animals Chapter 24 24.2 Animal Body Plans Symmetry • Similarity or balance among body structures of organisms • Asymmetry • Radial symmetry • Bilateral symmetry

18. Introduction to Animals Chapter 24 24.2 Animal Body Plans Cephalization • The tendency to concentrate nervous tissue and sensory organs at the anterior end of the animal

19. Introduction to Animals • Have a fluid-filled cavity with tissue formed from mesoderm that lines and encloses the organs in the coelom Chapter 24 24.2 Animal Body Plans Body Cavities • Coelomates

20. Introduction to Animals • Have a fluid-filled body cavity that develops between the mesoderm and the endoderm rather than developing entirely within the mesoderm Chapter 24 24.2 Animal Body Plans Body Cavities • Pseudocoelomates

21. Introduction to Animals Chapter 24 24.2 Animal Body Plans Body Cavities • Acoelomates • Have solid bodies without a fluid-filled body cavity between the gut and the body wall

22. Introduction to Animals Chapter 24 24.2 Animal Body Plans Development in Coelomate Animals • Protostomes • The mouth develops from the first opening in the gastrula. • Deuterostomes • The anus develops from the first opening in the gastrula. Visualizing Protostomes and Deuterostomes

23. Introduction to Animals Chapter 24 24.2 Animal Body Plans Segmentation • Segmented animals can be “put together” from a succession of similar parts. • Can survive damage to one segment • Movement is more effective

24. Segmentation!

25. Michel Angelo’s David