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Invertebrate evolution


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Evolutionary Biology

Published in: Science
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Invertebrate evolution

  1. 1. Invertebrate Evolution
  2. 2. Kingdom: Animalia Animal classification placed into related phyla or division 1. Invertebrates— majority of animals which lack a backbone 2. Vertebrate-- animals with a backbone Common Phyla: Porifera Cnidarians Platyhelminthes Nematodes Annelids Mollusks Arthropods Echinoderms Chordates
  3. 3. Origin of Invertebrates Invertebrate fossils, dating between 575 and 543 million years ago.
  4. 4. The Fossils Flat Plate shaped Segmented Bilateral symmetry Soft tissues Lived on shallow seas Nutrients: surrounding water
  5. 5. Beginnings of Invertebrate Diversity By the Cambrian Period, 544 million years ago, some animals had evolved shells, skeletons, and other hard body parts.
  6. 6. The animals of the Burgess Shale body symmetry Segmentation  skeleton front and a back end appendages adapted for many functions
  7. 7. Invertebrate Phylogeny features evolved during the Cambrian period such as: tissues and organs patterns of early development body symmetry cephalization segmentation formation of three germ layers and a coelom
  8. 8. Invertebrate Evolutionary Relationships
  9. 9. Evolutionary trends toward Greater size Compartmentalization Integration of specialized activities that keep the organism alive
  10. 10. I. Level of Organization Cellular: no true tissues; sponges Organ: have ectoderm, endoderm, and mesoderm; majority of animals Tissue: have ectoderm and endoderm; cnidarians like hydra
  11. 11. Body Symmetry Asymmetrical Radial Symmetry Bilateral symmetry
  12. 12. Cephalization  concentration of sense organs and nerve cells in the front of the body.
  13. 13. Type of Body Cavity Acoelomate Pseudocoelomate Coelom
  14. 14. Acoelomate Digestive sac (from endoderm) Tissue-filled region (from mesoderm) Body covering (from ectoderm)
  15. 15. Pseudocoelomate Body covering (from ectoderm) Muscle layer (from mesoderm) Digestive tract (from endoderm) Pseudocoelom
  16. 16. Coelomate Body covering (from ectoderm) Tissue layer lining coelom and suspending internal organs (from mesoderm) Coelom Digestive tract (from endoderm)
  17. 17. Segmentation Repetition of body parts Leads to specialization of body parts
  18. 18. Embryological Development Blastopore: first opening during the embryonic stages of an organism
  19. 19. Sponges: Multicellular Phylum Porifera Saclike Body with many Pores Filter Feeders Asexual and Sexual Reproduction Spicules
  20. 20. Simple Sponge Anatomy
  21. 21. Cnidarians Jelly fishes, corals, sea anemones Radial, tentacled carnivores Gastrovascular cavity True epithelial tissues with a jellylike matrix in between Simple nervous system
  22. 22. Flatworms (Phylum Platyhelminthes) Paired nerve cords Simplest animals with organ systems Free-living turbellarians
  23. 23. PhylumAnnelida Muscles and fluid in chambers act as a hydrostatic skeleton Nervous system Digestive and excretory system Closed circulatory system Segmented worms
  24. 24. secretory organ head end
  25. 25. Mollusks (Phylum Mollusca) 100,000 named species Including gastropods (snails), bivalves (scallops), chitons, nudibranchs, cephalopods
  26. 26. Cephalopods
  27. 27. Roundworms (Phylum Nematoda) Organ systems in a false coelom A complete gut Cylindrical body with bilateral features Some agricultural pests and human parasites Free-living decomposers or parasites More than 22,000 kinds of roundworms
  28. 28. Parasitic Roundworms
  29. 29. Simple Arthropods  Trilobite, millipede, centipede
  30. 30. Arthropod Characteristics Specialized and fused segments (wings) Efficient respiratory and sensory structures (eyes, antennae) Jointed appendages Hardened exoskeleton Key arthropod adaptations
  31. 31. Echinoderms Adults are radial, but bilateral traits appear in larval stages Water-vascular system with tube feet Exoskeleton with spines, spicules, or plates of calcium carbonate Sea stars, sea urchins, sea cucumbers, etc.
  32. 32. Summary Many important traits evolved in invertebrates. segmentationCoelom formation Cephalization Symmetry Organs Tissues Multicellurarity