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How many lines of symmetry?

How many lines of symmetry?. Fertilized egg. Zygote is one diploid cell made by the fusion of the sperm and egg. In humans this is internal fertilization within the fallopian tubes. Many other organisms have external fertilization where the egg and sperm are both released outside the parent.

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How many lines of symmetry?

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  1. How many lines of symmetry?

  2. Fertilized egg • Zygote is one diploid cell made by the fusion of the sperm and egg. • In humans this is internal fertilization within the fallopian tubes. • Many other organisms have external fertilization where the egg and sperm are both released outside the parent.

  3. 8 cell stage (blastocyst) morula blastula gastrula

  4. Germ layers • 3 kinds: • Ectoderm • Mesoderm • Endoderm • Layers of cells that work together to form specific tissues. • Sponges (0), cnidarian (2), others (all three)

  5. Body plans: Coelom

  6. If three germ layers, then….

  7. Porifera Sponges Sessile Adults Motile Larvae Assymetry Very Primitive- “barely” multicellular Classified by hard skeletal spines called spicules

  8. spicules

  9. http://www.youtube.com/watch?v=BW05vMziy2o Sponges spawning http://www.youtube.com/watch?v=SHJOu9PjKyU Investigating sponges

  10. Body of sponge • Osculum: opening at the top • Ostia: openings in the wall of sponge

  11. Cnidaria • Alternation of generations: Most have both stages in life cycle • Medusa: motile/sexual/tentacles down/mouth down • Polyp: sessile/asexual/ mouth up/tentacles up

  12. Characteristics of Cnidaria • Nematocyst stingers Nerve net (no brain)

  13. Hydra Hydra catching food: http://www.youtube.com/watch?v=Kukv0AtIVdU&feature=related Hydra; http://www.youtube.com/watch?v=yqXkaZwiu6s&feature=related

  14. http://www.youtube.com/watch?v=v9j9iO6Zy4o&feature=PlayList&p=E9E1093124E2F9C9&playnext=1&index=3; jellyfish movement • http://www.youtube.com/watch?v=M9MMp7QX6e0&feature=PlayList&p=E9E1093124E2F9C9&playnext=1&index=2 polyp stage

  15. Cnidarians

  16. Portuguese Man-of-War are colonies of four kinds of highly modified polyps: feeding polyps, reproductive polyps, etc.. Hydra Hydra catching food: http://www.youtube.com/watch?v=Kukv0AtIVdU&feature=related Cnidaria: hydrozoa

  17. Phylum Ctenophora: close relatives to cnidaria but jelly instead of stingers • Comb jellies http://www.youtube.com/watch?v=G7WT81ukHZE

  18. Platyhelminthes FLATWORMS • Tapeworms, Flukes (parasites), free swimming (planaria)

  19. Cephalization Notice the front end has sensory organs (HEAD?) Most are parasitic and don’t have cephalization, but platyhelminthes were first to have it.

  20. Characteristics • Acoelomate/ • No coelom/organs • Highly branched • Digestive system as they have no circulatory system

  21. Flatworm videos http://www.youtube.com/watch?v=voMKJea91gg free living flatworm http://www.youtube.com/watch?v=Ich4Y_K6GuM&feature=PlayList&p=E9E1093124E2F9C9&playnext=1&index=11 planaria eating http://www.youtube.com/watch?v=T6pAfQInf2c tapeworm in intestine

  22. Fluke • All parasitic • Most famous is the Sheep liver fluke that causes schistosomiasis. • Over 100 million in the world have this fluke/disease.

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