Introduction to Animals: Characteristics, Body Plans, Sponges, and Cnidarians

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 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.

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 • Exoskeletons • Hard or tough outer coverings that provide a framework of support • Protect soft body tissues • Provide protection from predators

6. 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

7. 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.

8. 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

9. 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

10. 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.

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

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 • Bilateral symmetry

17. 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

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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.

24. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians A Sponge

25. 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.

26. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Archaeocytes • Specialized cells that secrete spicules, which are the support structures of sponges • Spicules are small, needlelike structures made of calcium carbonate, silica, or a tough fibrous protein called spongin

27. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Sponge Diversity • Demospongiae • Calcarea • Hexactinellida

28. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Reproduction • Reproduce asexually • Fragmentation • Budding • Gemmules • Reproduce sexually • Eggs remain within a sponge. • Sperm are released into the water.

29. 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

30. 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.

31. http://en.wikipedia.org/wiki/Cnidocyte 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.

32. 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.

33. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Response to Stimuli • A nerve net conducts impulses to and from all parts of the body. • The impulses cause contractions of musclelike cells in the two cell layers.

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

35. 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. A Cnidarian

36. Introduction to Animals Chapter 24 24.3 Sponges and Cnidarians Cnidarian Diversity • Hydroids • Jellyfishes • Sea anemones and corals Comparison of Sponges and Cnidarians Part 1Part 2