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Porifera, Cnidarians, and Ctenophores

Porifera, Cnidarians, and Ctenophores. Rupp Bio II. Invertebrates. No backbone No shared characteristics 12 phyla One million species 97% of all animals. Porifera Background. Sponges No gastrula stage No true tissues or organs Approx. 10,000 species, only 150 are freshwater Sessile

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Porifera, Cnidarians, and Ctenophores

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  1. Porifera, Cnidarians, and Ctenophores Rupp Bio II

  2. Invertebrates • No backbone • No shared characteristics • 12 phyla • One million species • 97% of all animals

  3. Porifera Background • Sponges • No gastrula stage • No true tissues or organs • Approx. 10,000 species, only 150 are freshwater • Sessile • 1cm long to 2m in diameter

  4. Porifera Body Plan • Two layers • Closed at bottom, open at top, and hollow • Collar cells, pores, osculum

  5. Porifera Body Plan Continued

  6. Three Types of Sponges • Those made with spongin, which is a support fiber • Those made with spicules, which are hard particles of calcium carbonate and silicon dioxide • Combination of spongin and spicules

  7. Feeding • Filter feeders • Food sources • Bacteria • Protozoans • Algae • Organic matter • Collar cells to amoebocytes to water to osculum

  8. Reproduction—asexual Budding Gemmulation • Offspring forms as an outgrowth of the parent • If the bud does not separate a colony will form • A cyst-like reproductive unit formed in freshwater sponges • Formed in summer or fall and can overwinter • Like a seed or spore

  9. Reproduction—asexual con’t.

  10. Reproduction—asexual con’t. • Regeneration—restoration or new growth of tissue that may have been injured or lost

  11. Reproduction—sexual • Sperm are pulled in by the collar cells • Collar cells give the sperm to the amoebocytes • Amoebocytes deliver sperm to the eggs • Fertilization • Larva form • Larva are releases into the environment through the osculum • Larva will develop into adults after cellular reorganization—metamorphosis

  12. Reproduction—sexual con’t. • Some sponges are hermaphrodites • Self-fertilization is rare • Cross-fertilization is productive for genetic variety • All can produce eggs, therefore greater offspring numbers • Some species maintain gender

  13. Cnidarians and Ctenophores • Radially symmetrical invertebrates • Have tissues and a few simple organs • Aquatic and most are marine

  14. Cnidarians and Ctenophores—structure and function • Two shapes • Vase or polyp which is sessile • Bell or medusa which is mobile • Two layer construction • Epidermis • Gastrodermis • Mesoglea—jelly-like layer between epidermis and gastrodermis • Gastrovascular cavity • Tentacles around mouth

  15. Hydra Which type of body structure does this organism exhibit?

  16. Jellyfish Which type of body structure does this organism exhibit?

  17. Nay Nay’s Handywork National Zoo, Washington D. C.

  18. Coral Which type of body structure does this organism exhibit?

  19. Cnidarian and Ctenophore—feeding and defense • Cnidocytes—specialized defense and prey capture cells • Nematocysts—stinging cell within the cnidocyte • Located on tentacles • Trigger present • When triggered a filament extends to deliver the sting, poison, or wrap the intruder • Prey captured, moved into mouth, nutrients absorbed, prey expelled through mouth

  20. Cnidarians and Ctenophores—nervous system • Nerve net • Stimulus-response action—no thinking • Entire body contracts • Feeding and swimming are coordinated by the nerve net • Stimulus to nerve net to epidermis to contraction

  21. Cnidarian classification • Three classes • Hydrozoans • Only polyps • Only medusas • Alternate generations • Mixed colonies • Scyphozoans • Medusa • Anthozoans • Polyps

  22. Hydrozoans • 3700 species • Typically marine and colonial • Obelia • Polyps on stalks • Some feed, others reproduce • Physalia • Portuguese man-of-war • Colony of medusas and polyps • Gas-filled float • Polyps • Feeding and digestions • Reproduction • Huge numbers of cnidocytes

  23. Hydrozoans—Hydra • Very unique • Only polyps • Freshwater • Not colonial • Can be green due to symbiotic relationship with algae • Capable of movement • Gas bubble float • Somersaulting • Asexual reproduction—budding in warm weather • Sexual reproduction—cool fall weather triggers gamete formation • Hermaphroditic • Male • Female

  24. Scyphozoans • Name means “cup animals” • Dominant form is the medusa • Jellyfish • 2cm to 4 m in size • Aurelia • Alternation of generations

  25. Anthozoans • Name means “flower animals” • 6100 marine species • Anemones and corals • Anemones • Polyps • Feed on fish • Symbiotic relationship with clown fish • Corals • Small colonial polyps • Connect to each other with CaCO3 skeletons • Form reefs • Tropical dwelling • Symbiotic with algae for extraction of calcium from sea water, therefore shallow living

  26. Anthozoans Anemones Corals

  27. Ctenophores • Approximately 100 species • Marine dwelling • Comb-like rows of cilia • Often called comb jellies • Cilia are used for movement as opposed to contractile swimming—largest organisms to move this way • Colloblasts instead of cnidocytes • Secrete a sticky substance • Binds prey • Located on two tentacles • Apical organ at one end of body allows a sense of orientation in water—nerves in apical organ coordinate cilia • Bioluminescent

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