24.1 Animal Characteristics

1. Introduction to Animals Chapter 24 24.1 Animal Characteristics General Animal Features • 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.

2. 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.

3. 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

4. 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

5. Introduction to Animals Chapter 24 24.1 Animal Characteristics Gut (where food travels when eaten) • 1-way gut • Has 2 openings (mouth and anus) in which food travels in 1direction. • 2-way gut • Has 1 opening in which food goes in and waste leaves through same opening • Gutless • No gut (like a sponge)

6. Introduction to Animals Chapter 24 24.1 Animal Characteristics 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.

7. 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

8. 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

9. 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.

10. Introduction to Animals Chapter 24 24.1 Animal Characteristics

11. Introduction to Animals Chapter 24

12. 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

13. Introduction to Animals Chapter 24 24.1 Animal Characteristics

14. 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.

15. Introduction to Animals Chapter 24 24.2 Animal Body Plans

16. Introduction to Animals Chapter 24 24.2 Animal Body Plans Symmetry • Similarity or balance among body structures of organisms • Asymmetry • Radial symmetry (ex. hydra, and starfish) • Bilateral symmetry (ex. Humans and butterflies)

17. Introduction to Animals Chapter 24 24.2 Animal Body Plans Directional Terms • Anterior • In front of, front • Posterior • Behind, toward the rear • Distal • Away from, father from the origin • Proximal • Near, closer to the origin

18. Introduction to Animals Chapter 24 24.2 Animal Body Plans Directional Terms • Inferior • Below, under • Superior • Above, over • Lateral • Away from the middle, toward the side • Medial • Toward the midline, middle, away from the side • Dorsal • Near the upper surface, towards the back • Ventral • Toward the bottom, belly surface

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