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The Design of Organisms

The Design of Organisms. What Patterns do you see?. Body Plans. The great diversity of plant and animal forms arises from a surprisingly small number of patterns. Although some organisms have complex shapes, we will begin looking at simple systems. Spheres, Tubes, and Fans.

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The Design of Organisms

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  1. The Design of Organisms What Patterns do you see?

  2. Body Plans • The great diversity of plant and animal forms arises from a surprisingly small number of patterns. • Although some organisms have complex shapes, we will begin looking at simple systems

  3. Spheres, Tubes, and Fans • A surprisingly large number of biological structures can be described in terms of spheres, tubes, and fans (surfaces).

  4. Phylum Annelida: The Segmented Worms

  5. Annelid Evolution • Earliest fossils are about 520 to 550 million years old… right at the beginning of the Cambrian period.

  6. Annelid Characteristics 1. Bilaterally symmetrical and vermiform (worm-shaped)

  7. 2. Triploblastic • 3 cell layers

  8. 3. Coelom (Body Cavity)

  9. More Characteristics • 4. Through Gut: Mouth & Anus • 5. No true respiratory system (no respiratory organs)

  10. 6. Simple Nervous System • Ganglia are bundles of nerves that act somewhat like brains. • The head contains several “cerebral ganglia” • Along the ventral nerve cord (yellow) there are “segmental ganglia”

  11. 7. Closed Circulatory System with “Hearts” • Annelid worms have blood and 5 pairs of “hearts” to keep it circulating. • This is a new characteristic, not seen in simple organisms.

  12. 8. Body possesses 3 separate sections, a prostomium, a trunk and a pygidium. • Prostomium = 1st segment, some w/ sensory organs • Trunk = body segments • Pygidium = end segments, contain anus.

  13. 9. Reproduction: Freaky Worms • Some annelid worms are gonochoristic. Gonochoristic organisms, like you, have a distinct sex. Usually, there are 2 varieties, i.e. male and female. • Most however, are simultaneous hermaphrodites, meaning that individuals have both testes and ovaries. During mating, they may act as a male or female.

  14. Clitellum • Fertilized eggs will be wrapped in a mucus-covered coccoon made by the clitellum, which contains the worm eggs

  15. Label ‘er up! • Label up your diagram! • Skip “C” • B = “ganglia” not brain

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