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Animals: The Invertebrates

Animals: The Invertebrates. Chapter 23. Key Concepts:. All animals are multicelled, aerobic heterotrophs Animals originated about 900 million years ago

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Animals: The Invertebrates

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  1. Animals: The Invertebrates Chapter 23

  2. Key Concepts: • All animals are multicelled, aerobic heterotrophs • Animals originated about 900 million years ago • Comparisons of body plans of existing animals with fossil records reveal that there were several trends in the evolutions of certain lineages

  3. Key Concepts: • Divergences gave rise to two major lineages: those of the mollusks, annelids, and arthropods and the other one to the echinoderms and chordates • The arthropods, especially the insects, have been the most successful animal groups

  4. Evolutionary Tree Diagram

  5. Overview of the Animal Kingdom • Animals • Multicellular • Heterotrophs • Oxygen is required • Sexual reproduction (some asexual) • Motile - in part of life cycle • Embryonic development • Mitotic cell divisions in embryo • Tissue layers • Ectoderm, Endoderm, Mesoderm

  6. Vertebrates Mammals birds, reptiles, amphibians, fishes Invertebrates No backbones Body symmetry & Cephalization ( sense in the head) Gut Body cavity Segmentation Diversity in Body Plans

  7. Examples of Body Symmetry • Radial • Live in water • Bilateral • Mirror image

  8. Type of Body Cavity in Animals • Gut, body cavities, segmentation

  9. Type of Body Cavity in Animals • Lined body cavity

  10. SpongesSuccess in Simplicity • No symmetry, tissues, or organs

  11. SpongesSuccess in Simplicity A basket sponge releasing a cloud of sperm

  12. Tissues in a Jellyfish The sea nettle, a jellyfish (Chrysaora)

  13. Stages in Cnidarian Life Cycles • Both polyp and medussa body forms Physalia Portuguese Man-of-War

  14. Flatworms:Turbellarians, Flukes & Tapeworms Nervous system in a Planarian Reproductive system in a Planarian

  15. Parasitic Scolex Proglottids Hermaphroditic Tapeworms

  16. Roundworms • Most abundant multicelled animal • Bilateral symmetry • Cylindrical body • Cuticle • Complete digestive system • Male and female

  17. Parasitic Sexual or asexual phases Two hosts Snail Human Flukes Life Cycle of Schistosoma japonicum

  18. Mollusk Soft body Shell Mantle Fleshy foot Gastropods-snails Chitons Bivalves-clams Cephalopods-squid A Sampling of Mollusks

  19. Evolutionary Experiments with Body Plans Radula is used to scrape food into the mouth

  20. Evolutionary Experiments with Body Plans Body Plan of a clam

  21. Evolutionary Experiments with Body Plans Body Plan of a cuttlefish, a cephalopod

  22. Annelids: Segments Galore • Bilateral • Segmented • Earthworms • Leeches • Polychaetes

  23. Earthworm Body Plan Coelomic chambers A nephridium

  24. Earthworm Body Plan Portion of the closed circulatory system Part of the digestive system

  25. Earthworm Body Plan Part of the nervous system

  26. Arthropods: The Most Successful Organisms on Earth-Arthropods • Over one million species • Trilobites (extinct) • Chelicerates • Spiders • Crustaceans • Barnacles and crabs • Uniramians • Centipedes, millipedes, insects

  27. Adaptations of Insects and Other Arthropods • Hardened exoskeleton • Jointed appendages • Fused and modified segments • Respiratory structures • Specialized Sensory Structures • Division of labor

  28. A Look at Spiders Organization of a Spider Body

  29. A Look at Crustaceans • Shrimps, lobsters, crabs, barnacles A Copepod A Lobster

  30. Life Cycle of a Crab Continuous molting

  31. A Look at Insect Diversity • Head, thorax, abdomen • Sensory antennae • Mouthparts • 3 pairs of legs • 2 pairs of wings • Malphigian tubules • Waste disposal • Life cycles

  32. A Look at Insect Diversity Examples of Appendages Grasshopper Butterfly Mosquito Fly

  33. Examples of Post-Embryonic Development Silverfish True bugs Fruit flies

  34. Echinoderms Sea star Sea urchin Sea cucumber Brittle stars Body walls Spines, spicules Radial symmetry Decentralized nervous system Water-vascular system The Puzzling Echinoderms

  35. The Puzzling Echinoderms Sea urchin

  36. Key Aspects of the Radial Body Plan of a Sea Star

  37. In Conclusion • Animals are multicellular, aerobic heterotrophs that ingest or parasitize other organisms • Animals range from structurally simple placozoans and sponges to vertebrates

  38. In Conclusion • Almost all animals more complex than cnidarians show bilateral symmetry, form tissues, organs, and organ systems • All mollusks have a fleshy soft body, and a mantle

  39. In Conclusion • The annelids, have a segmented body, complex organs, and coelomic chambers • Arthropods are the most successful of all groups in terms of diversity, numbers, distribution, defenses, and capacity to exploit food resources • Echinoderms have spines, spicules, or plates in their body wall • developed by M. Roig

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