Phylum cnidaria

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Phylum cnidaria

  1. 1. Phylum Cnidaria The Stingers
  2. 2. 4 Classes we’ll cover:• Hydrozoa• Anthozoa• Scyphozoa• Cubozoa
  3. 3. Shared Traits• Radial symmetry• Carnivorous• Reproduce sexually and asexually• Polyp and medusa form – Polyp: sac-like stage with waving tentacles, nonmotile and benthic – Medusa: bell-like stage, hanging tentacles, motile and planktonic
  4. 4. Body Layers & Parts• Ectoderm/Epidermis: outside layer containing stinging cells (nematocysts)• Tentacles: used for food capture, lined with nematocysts• Endoderm/Gastrodermis: lines the gut, cells here aid in digestion (absorption of stung prey)• Mesoglea: jelly-like substance found between the above two layers• Mouth and anus are the same opeining
  5. 5. Polyp Phase and Medusa Phase
  6. 6. Nematocysts• Coiled firing cells that shoot toxin into prey• Most not deadly to humans as they aren’t usually able to penetrate our skin• Some fatal
  7. 7. Class Anthozoa – Corals
  8. 8. Class Anthozoa – Anemones
  9. 9. Class Anthozoa – Sea Pens
  10. 10. Class Anthozoa – generalities• Largest group of Cnidarians• Stay polyps their whole lives• Solitary or colonial• Example: Sea Anemones, Corals, Sea Pens
  11. 11. Corals – Special Characteristics• Hard corals – calcium forming• Contain zooxanthellae, a symbiotic dinoflagellate• Soft corals – less calcium, more flexible protein structure• Great Barrier Reef off Australia-world’s largest living structure.• Most corals need shallow, salty water
  12. 12. Anatomy of a Coral Polyp Corals eat (capture foodusing tentacles) as well asmake their own food (via zooxanthellae)
  13. 13. Coral Reef Issues
  14. 14. Class Hydrozoa• Can have just a polyp stage, just a medusa stage, or both• Can join to form complex colonies, like Portuguese Man O’ War (see next slide)
  15. 15. Class Hydrozoa
  16. 16. Class Scyphozoa• Medusa is the dominant life stage• Move with rhythmic contractions
  17. 17. Class Scyphozoa

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