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Chapter 28

Chapter 28. The Animal Kingdom: An Introduction to Animal Diversity. Characteristics common to most animals Eukaryotic Multicelleular Heterotrophic Specialized cells. Characteristics common to most animals, cont. Capable of locomotion at some point

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Chapter 28

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  1. Chapter 28 The Animal Kingdom: An Introduction to Animal Diversity

  2. Characteristics common to most animals • Eukaryotic • Multicelleular • Heterotrophic • Specialized cells

  3. Characteristics common to most animals, cont. • Capable of locomotion at some point • Can respond adaptively to external stimuli • Can reproduce sexually

  4. Characteristics common to most animals, cont. • Sexual reproduction • Sperm and egg unite to form a zygote • Zygote undergoes cleavage • Multiple cell divisions result in a blastula • Blastula undergoes gastrulation

  5. Advantages of life in the ocean • Relatively stable temperatures • Provide buoyancy • Provide food • Fluid and salt balances are most easily maintained in this environment

  6. Disadvantages of life in the ocean • Currents • Other water movements

  7. Disadvantages of life in fresh water • Less constant environment • Less food • Fresh water is hypotonic to tissue fluid, osmoregulation required

  8. Disadvantages of terrestrial life • Potential for dessication • Temperature change • Gametes and embryos must be protected

  9. Animals classified according to body plan • Asymmetrical (most sponges) • Radial (phylum Cnidaria) • Biradial (sea anemones and ctenophores) • Bilateral (most animals)

  10. Radial symmetry

  11. Bilateral symmetry

  12. Animals classified on the basis of tissue development • Diploblastic • Ectoderm • Endoderm • Triploblastic • Ectoderm • Endoderm • Mesoderm

  13. Ectoderm gives rise to • Body covering • Nervous system • Endoderm gives rise to • Gut lining • Digestive organs • Mesoderm gives rise to • Most other body structures

  14. Triploblasts classified according to type of coelom • Acoelomates • Coelomates • Pseudocoelomates • Protostomia • Deuerostomia

  15. Acoelomate – flatworm (liver fluke)

  16. Pseudocoelomate - nematode

  17. Coelomate - vertebrate

  18. Pseudocoelomates were formerly classified as a separate group • Probably not a monophyletic group • Probably evolved through simplification from multiple groups of coelomates

  19. Two main groups of coelomates • Protostomia • Deuterostomia

  20. Protostomia • Spiral cleavage • Cell divisions diagonal to polar axis, therefore spiral arrangement of cells • Deuterostomia • Radial cleavage • Cell divisions parallel or at 90°, therefore cells directly above or below each other

  21. Spiral cleavage

  22. Radial cleavage

  23. Phylogeny has three major clades of coelomates • Protostomia • Lophotrochozoa • Ecdysozoa • Deuterostomia

  24. Five main animal clades: ParazoaRadiata LophotrochozoaEcdysozoa Deuterostomia

  25. In protostomes, blastophere develops into the mouth • In deuterostomes, the blastophore usually becomes the anus

  26. Protostomes • Lophotrochozoa • Platyhelminthes • Nemerteans • Mollusks • Annelids • Lophophorate phyla • Rotifers

  27. Protozomes, cont. • Ecdysozoa • Nematodes • Arthropods

  28. Deutostomes • Echinoderms • Chordates

  29. Phylum Porifera • Choanocytes: animals with flagellate collar cells • Sole parazoa • Sponge body consists of • Sac with tiny openings • Spongocoel • Osculum • Cells do not form true tissues

  30. A simple sponge cut open to expose its organization. Water drawn through the pores passes through the spongocoel and exits through the osculum. Collar cells trap food particles in the stream of water

  31. Phylum Cnidaria • Radial symmetry • Two tissue layers • Cnidocytes (cells with nematocysts) • Gastrovascular cavity has single opening (both mouth and anus)

  32. Gonothyraea loveni Montastrea cavernosa Chrysaora fuscescens

  33. Phylum Cnidaria, cont. • Irregular, non-directional nerve nets • Nerve nets connect sensory cells with contractile and gland cells • Life cycle of many cnidarians includes • Sessile polyp stage • Free-swimming medusastage

  34. Phylum Cnidaria has three main classes • Hydrozoa • Scyphozoa • Anthozoa

  35. Hydrozoa are usually polyps and may be solitary or colonial • Hydras • Hydroids • Portuguese man-of-war

  36. Hydra, afreshwater hydrozoan

  37. Scyphozoa are generally medusae • Jellyfish • Anthozoa are polyps and may be solitary or colonial; they differ from hydrozoans in the organization of the gastrovascular cavity • Sea anemones • Corals

  38. Phylum Ctenophora • Comb jellies are fragile, luminescent marine predators • Biradial symmetry • Eight rows of comb-like cilia • Diploblastic • Tentacles with adhesive glue cells

  39. Ctenophore (comb jelly)

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