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Evolutionary Trends

Evolutionary Trends. 1. Trends in Symmetry 2. Trends in Digestive Tracts 3. Trends in Body Cavities 4. Trends in Cephalization 5. Trends in Segmentation. Symmetry. Asymmetry ( No Symmetry ) Radial Symmetry Bilateral Symmetry. Asymmetrical Sponge. Radial Symmetry. Bilateral Symmetry.

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Evolutionary Trends

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  1. EvolutionaryTrends 1. Trends in Symmetry 2. Trends in Digestive Tracts 3. Trends in Body Cavities 4. Trends in Cephalization 5. Trends in Segmentation

  2. Symmetry • Asymmetry ( No Symmetry ) • Radial Symmetry • Bilateral Symmetry

  3. AsymmetricalSponge

  4. Radial Symmetry

  5. Bilateral Symmetry

  6. ??

  7. ??

  8. ??

  9. Digestive System • Incomplete • Complete

  10. Incomplete

  11. Complete Digestive System

  12. Body Cavity • Acoelom (No Coelom ) • Pseudocoelom (False Body Cavity) • Coelom (True Coelom)

  13. Acoelomate (no body cavity)

  14. Acoelom

  15. Pseudocoelom false body cavity this body cavity is located between the mesoderm and endoderm

  16. Coelom true body cavity This body cavity is located within the mesoderm

  17. Protostomes and Deuterostomes • Protostomes or “First Mouth Animals” During their embryonic development the mouth forms first and the anus second. • Deuterostomes: “Second Mouth Animals” During their embryonic development the anus forms first and the mouth second.

  18. Blastula

  19. Early Gastrulation

  20. Late Gastrulation

  21. Is this larva a protostome or deuterostome?

  22. Larva Deuterostome Protostome

  23. Sponges (Porifera)

  24. Cnidaria

  25. The Two Basic Body Forms

  26. Life Cycle of Obelia

  27. Flatworms (Platyhelminthes) • Fluke

  28. Tapeworms

  29. Nematoda • Roundworms are round in cross section rather than flat. • The most abundant animals on earth. • Biologist A.M.Cobb once said that if all our planet’s land and seas were swept away, but with the nematodes somehow stayed in place, a clear outline of the earth and its geological features would remain.

  30. Nematoda

  31. The Advantages of a Coelom or a Pseudocoelom • The reproductive and digestive organs can evolve more complex shapes and functions. • The gut tube and other organs are cushioned and thus better protected. • Can act as hydroskeleton providing support and rigidity for the soft animal. • The activities of the suspended gut can take place undisturbed by the activity of the animal’s outer body wall.

  32. Molluscan Body Plan

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