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Cnidarians & Ctenophorans

Cnidarians & Ctenophorans. 1. CNIDARIANS. 2. Phylum Cnidaria. About 9000 species Most are marine (jellyfish, coral, sea anemones, Portuguese man-of war) Hydras are found in freshwater All have arm-like tentacles. 3. Cnidarian Characteristics. Radial symmetry

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Cnidarians & Ctenophorans

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  1. Cnidarians & Ctenophorans 1

  2. CNIDARIANS 2

  3. Phylum Cnidaria • About 9000 species • Most are marine (jellyfish, coral, sea anemones, Portuguese man-of war) • Hydras are found in freshwater • All have arm-like tentacles 3

  4. Cnidarian Characteristics • Radial symmetry • Hollow gut -Gastrovascular cavity has single opening (serves as both mouth and anus) • Two tissue layers (diploblastic) • Outer epidermis and inner gastrodermis 4

  5. Cnidarian Characteristics • Either tubular or bell shaped • Tentacles surround mouth • Only animal with cnidocytes (stinging cells) found in the tentacles • Nematocyst – coiled, harpoon-like stinger inside cnidocyte that shoots out 5

  6. Cnidarian Characteristics • Cnidocytes contain poison to paralyze prey • Tentacles bring food into mouth • Inner gastrodermis secretes digestive juices into gastrovascular cavity which digests food and circulates nutrients 6

  7. Extracellular Digestion Food digested outside of cells 7

  8. Have asimplenerve net & sensory receptors Muscles help in directional movement & capturing prey Cnidarian Systems

  9. mesoglea-filled bell tentacles Jellylike mesoglea between two cell layers supports cnidarian 9

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  11. Cnidarian Diversity • Scyphozoans: • Jellyfish • Anthozoans: • Sea anemones • Corals • Hydrozoans: • Hydra • Cubozoa • Box Jellies 11

  12. Cnidarian Diversity Jellyfish Coral polyps Sea Anemone Coral polyps 12

  13. Anthozoans

  14. Anthozoan Characteristics • Sea Anemones • Brightly colored & Resemble flowers • Solitarypolyps • Feed on invertebrates & fish Corals • Most are colonial • Build limestone case • Live as polyps in their case

  15. Sea Anemones & Coral • Exist only as Polyps • Clownfish live in anemone tentacles • Corals build a limestone case which build up & form reefs ANEMONE CORAL

  16. Hydrozoans • Hydra • Exist only as polyps • Reproduce by budding • Freshwater only • Form resistant zygotes when environment is bad • Move by somersaulting with tentacles

  17. Hydra

  18. ColonialHydrozoan(not a single organism Tentacles sting prey such as fish & humans Polyps in colony feed Has gas-filled air float Portuguese man-of-war

  19. Cubozoans Box JellyFish 19

  20. Scyphozoans

  21. Scyphozoan Characteristics • Jellyfish • Medusa is dominant body form • Go through small polyp stage during life cycle • Stinging tentacles • May live close to shore or the open ocean

  22. Parts of a Jellyfish 22

  23. Jellyfish Life Cycle

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