Quiz!

1. What is the purpose of an exoskeleton? What does “sessile” mean? Do sponges have internal or external fertilization? What kind of symmetrical are you? Is your bellybutton on your dorsal or ventral side? Quiz!

2. 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.

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 Reproduction • Fertilization occurs when the sperm penetrates the egg to form a fertilized egg cell called the zygote. • Internal fertilization • External fertilization

7. 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

8. 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.

9. Introduction to Animals Chapter 24 24.1 Animal Characteristics

10. Introduction to Animals Chapter 24

11. 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.

12. Introduction to Animals Chapter 24 24.2 Animal Body Plans

13. 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)

14. 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

15. 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

16. 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

17. 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

18. 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

19. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Sponges • Sponges do not develop tissues. • Collar cells with flagella line the inside of the sponge and whip back and forth drawing water into the body of the sponge. • Water and waste materials are expelled from the sponge through the osculum. • Asymetrical • Sessile

20. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians

21. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Filter Feeder • Food particles cling to the cells. • Digestion of nutrients takes place within each cell.

22. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Reproduction • Reproduce asexually • Fragmentation • Budding • Reproduce sexually • Eggs remain within a sponge. • Sperm are released into the water. • All sponges are hermaphrodites (have both egg and sperm)

23. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Cnidarians • Have one body opening and two layers of cells • Outer layer functions in protecting the internal body • Inner layer functions mainly in digestion • Radial Symmetry • 2-way gut

24. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Feeding and Digestion • Tentacles are armed with stinging cells called cnidocytes. • A nematocyst is a capsule that holds a coiled tube containing poison and barbs. • Water inside an undischarged nematocyst is under an osmotic pressure of more than 150 atmospheres.

25. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians • As the osmotic pressure increases, the nematocyst discharges forcefully. • A barb is capable of penetrating a crab shell.

26. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians • Cells lining the gastrovascular cavity release digestive enzymes over captured prey. • Undigested materials are ejected though the mouth.

27. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Reproduction • Two body forms • Polyp • Medusa

28. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians • The two body forms of cnidarians can be observed in the life cycle of jellyfishes.

29. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Cnidarian Diversity • Hydroids • Jellyfishes • Sea anemones and corals