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Phylum Cnidaria

Phylum Cnidaria

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Phylum Cnidaria

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  1. Phylum Cnidaria

  2. Phylum Cnidaria: Diagnostic Features • hydra, jellyfish, sea anemones, and corals • fresh water & marine • polymorphic (polyp & medusa forms) • benthic & planktonic • metazoans; tissue grade; diploblastic • radiate • predaceous

  3. Cnidocytes- stinging cells with nematocysts

  4. Histology • epidermis- epithelial muscle cells contain contractile fibers • gastrodermis- nutritive cells; flagellated; phagocytic • mesoglea- secreted, gelatinous layer between epidermis and the gastrodermis

  5. Physiology • nervous system: "nerve net" • respiration/excretion: diffusion/ammonia • reproduction: budding; sexual reproduction in medusae; planula larvae

  6. Classification • Class Hydrozoa • Class Scyphozoa • Class Anthozoa

  7. Class Hydrozoa (hydroids) • diversity- 2700 species • Obelia, Gonionemus, and Hydra • Craspedacusta; found in Oklahoma; contains symbiotic algae • Physalia- Portuguese Man-O-War; colonial pelagic hydrozoan; pneumatophores

  8. Portuguese Man-O-War

  9. Siphonophore

  10. Obelia: a colonial hydrozoan

  11. Obelia colony

  12. Craspedacusta

  13. diversity- 6000 spp. most marine example: Aurelia Class Scyphozoa (true jellyfish)

  14. Aurelia life cycle

  15. Class Anthozoa (anemones & corals) • polyp form only • all marine • endosymbiotic algae

  16. Coral Polyps

  17. Sea Fan

  18. Organ Pipe Coral

  19. Sea Anemone

  20. What is a coral reef? • most diverse marine ecosystems on earth • 200 million years in existence • growth ~ 1.3cm per year • calcium carbonate (CaCO3) • zooxanthellae (endosymbiotic algae)

  21. Where are the coral reefs? • Coral reefs require clean, clear water that ranges in temperature from 24-30 OC.

  22. Why does the coral reef need protection? • visitors are destroying the reef • touching, standing, or anchoring • boat propellers • oil

  23. Why does the coral reef need protection? • nutrient enrichment of coastal waters • septic tank leakage • wastewater outfall • shallow injection wells • fertilizers- nitrogen and phosphorus

  24. Phylum Ctenophora • “Comb Jellies”