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Lecture Exam I

Lecture Exam I. Cambrian radiation / phylogeny = 2 papers Systematics intro Protista: 10 phyla Animalia: Porifera, Cnidaria ~20 questions Short answer, essay, life cycle sketch. Phylum Cnidaria. 3 Classes: Anthozoa Scyphozoa Hydrozoa. Characteristics:. Diploblastic metazoan

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Lecture Exam I

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  1. Lecture Exam I • Cambrian radiation / phylogeny = 2 papers • Systematics intro • Protista: 10 phyla • Animalia: Porifera, Cnidaria • ~20 questions • Short answer, essay, life cycle sketch

  2. Phylum Cnidaria • 3 Classes: • Anthozoa • Scyphozoa • Hydrozoa

  3. Characteristics: • Diploblastic metazoan • Ectoderm and endoderm separated by acellular mesoglea • Nervous system: simple nerve net, neurons

  4. Development • Planula larvae • ciliated, motile, gastrula larva

  5. Radial symmetry • Modified into • biradial, quadradial, • etc…

  6. Gastrovascular cavity • Saclike, partitioned, or branched w/ one opening • = mouth and anus

  7. Alternating life history forms: polyp and medusa

  8. Polyp • Radial symmetry • Oral end = hypostome or manubrium in hydrozoans • flat pedal disc in anthozoans • Tentacles surround mouth

  9. PolypGastrovascular cavity • Circulation, digestion, distribution of nutrients • Hydrozoans: coelenteron is single tube • Scyphozoans: four longitudinal mesenteries • Anthozoans: compartmentalized by mesenteries

  10. Polyp: support • Hydrostatic, water-filled coelenteron • Anthozoans - bits of sediment and shell fragments in column wall for support • Hydrozoans - flexible horny perisac (periderm) of chitin from epidermis

  11. Polyp: movement • Retractor muscles: longitudinal fibers along mesenteries • Circular muscles: sphincters • in tentacles and oral disc • Most polyps sedentary or sessile • Creep slowly w/ pedal disc musculature • http://www.youtube.com/watch?v=-UI531GMRTM

  12. Medusa • All cnidaria except Anthozoa • Bell-, dish- or umbrella-shaped • Exumbrella: convex upper (aboral) surface • Subumbrella: concave lower (oral) surface • Mouth at center Free-floating, mouth down

  13. Medusa • External surface: epidermis • Internal surface: gastrodermis • Coelenteron central; extends to radial canals • Usually four radial canals, tentacles, stomach divided by mesenteries into four gastric pouches

  14. Nematocysts • Stinging structures

  15. Nematocysts: multiple types • Generic nematocyst (all) • Double-walled capsule w/ toxic mixture of phenols + proteins • Spines or barbs for penetration, anchor in victim • Spirocyst (Anthozoa) • Spring-like mechanism • Adhesive tubules wrap around and stick to victim • Ptychocyst (tube anemones) • Create capsule tubule

  16. Feeding and digestion Tentacles capture prey, carry to mouth, ingest whole Extracellular digestion in coelenteron • enzyme-producing cells

  17. Reproduction and DevelopmentHydrozoa • Polyps = asexual budding

  18. Reproduction and DevelopmentHydrozoan • Free-living hydromedusa • Dioecious, release sperm or eggs

  19. Reproduction and DevelopmentScyphozoa • Asexual reproduction: small polyp = scyphistoma • Medusa from scyphistoma • Immature medusa = ephyra • Most species dioecious

  20. Reproduction and DevelopmentAnthozoa • Exclusively polyps • Asexual reproduction • Fission • Pedal laceration: pedal disc spreads, anemone moves, leaves small fragments • develop into adult

  21. Class Hydrozoa Hydroids and hydromedusa

  22. Hydrozoa Portuguese Man-of-war Physalia

  23. Class Anthozoa Anemones, corals, sea pens Exclusively marine Octocorals • Soft corals • Gastraxonacea • Helioporaceans • Sea pens and sea pansies • Protoalcyonaria • Stoloniferans • Telestaceans Sea pen

  24. Class Anthozoa Anemones and true corals • True sea anemones • True corals (stony corals)

  25. Class Anthozoa • Black or thorny corals • Ceranthids or tube anemones

  26. Class Scyphozoa • Jellyfish

  27. Box jelly Chiropsalmus

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