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The Characteristics of Phylum Cnidaria

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  1. The Characteristics of Phylum Cnidaria

  2. Phylum Cnidaria Class Anthozoa Class Hydrozoa Class Scyphozoa Class Cubozoa Corals Anemones Hydra Portuguese Man-Of-War Stinging Limu Fire Coral True jellyfish Box jellies Sea wasps

  3. Characteristics of Phylum Cnidaria • radial symmetry • blind sac gut (= coelenteron or gastrovascular cavity) • diploblastic with mesoglea • polyp and medusa body forms • nematocysts (= specialized stinging capsules) • nerve net • lack excretory, circulatory & respiratory systems • complex life cycle • many colonial forms exhibiting polymorphism

  4. oral Radial Symmetry Polyp aboral

  5. Radial Symmetry JellyfishPhylum Cnidaria Medusa

  6. Blind Sac Gut

  7. Diploblastic- two germ layers Phylum Cnidaria

  8. Nematocysts

  9. Nematocyst Picture Nematocyst

  10. More Nematocysts http://www.youtube.com/watch?NR=1&v=-Tp38DUjUnM&feature=endscreen

  11. Nerve Net

  12. Diffusion Across the Body Wall

  13. Sea Anemones

  14. Circulation in a Moon Jellyfish

  15. The Cnidarian Life Cycle The Cnidarian Life Cycle

  16. Coloniality CoralPhylum Cnidaria

  17. General Characteristics of Cnidaria • Stinging cells • Two stages in life cycle (polyp & medusa) • Blind sack gut • Radial symmetry • Diploblastic • Hydrostatic skeleton • Nerve net • Many colonial, some solitary forms

  18. Class Hydrozoa (Gr. hydra, water serpent) • polyps and medusa stage, although polyp stage is dominant. • gut cavity of polyp is simple, lacking a pharynx and not divided by mesenteries. • tetramerous (four-part) radial symmetry. • gonads are ectodermal (found in the epidermis). • medusa stage may possess specialized balance organs called statocysts and photosensitive organs called ocelli. • solitary or colonials; some colonial forms highly polymorphic. • includes hydroids (“stinging limu”), fire coral, pink coral, and siphonophores.

  19. The Cnidarian Life Cycle The Hydrozoan Life Cycle

  20. Hydrozoan Colony

  21. Hydrozoan Colonies“Stinging Limu”

  22. Hydrozoan Medusa

  23. Hydrozoan Medusa

  24. Hydrocorals

  25. Fire Coral

  26. By-the-Wind-SailorA Floating Colony of Polyps

  27. Coloniality and Polymorphism

  28. Poly,orphism in the Portuguese Man- of-War

  29. Class Scyphozoa (Gr. skyphos, cup) • life cycle with both polyps and medusae, but medusae dominate with polyp stage reduced or absent. • polyp stage (scyphistoma) goes through strobilization to produce young medusa. • bell margin lacks a velum. • tetramerous (= four-part) radial symmetry. • gut divided into a complex system of radial canals. • some with a simple single mouth, but many with thousands of microscopic “mouths” at the ends of oral arms. • gonads endodermal (found in the gastrodermis). • specialized sense organs called rhopalia with ocelli & statocysts . • includes some 200 marine species. • "true" sea jellies.

  30. Moon Jelly Anatomy

  31. scyphistoma strobila Scyphozoan Life Cycle

  32. Sea Jellies

  33. Class Cubozoa (Gr. kybos, a cube) • polyps and medusae stages, but medusae dominate with polyp stage reduced. • polyp stage develops directly into medusa. • bell margin with a velarium. • tetramerous (= four-part) radial symmetry; bell cube-shaped with tentacles arising from each corner. • gonads endodermal (found in the gastrodermis). • specialized sense organs called rhopalia with ocelli & statocysts . • includes some 15 marine species. • includes box jellies and sea wasps.

  34. Seawasp Box Jellies

  35. Box Jelly Anatomy

  36. Class Anthozoa (Gr. anthos, flower) • lack medusa stage entirely (polyp forms only) • mouth with a tubular pharynx that projects inward into the gut • large gut cavity divided by mesenteries that radiate inwards from the body wall • gonads endodermal, borne on the mesenteries • hexamerous (6-part) or octamerous (8-part) radial symmetry or biradial (modified radial symmetry that limits the number of planes that can divide the body into equal halves • includes sea anemones, “true” stony corals, sea fans, sea pens, organ pipe coral, precious black coral, & zoanthids

  37. Subclass Zoantharia Order Actinaria Sea Anemones

  38. Sea Anemone Anatomy

  39. Subclass Hexacorallia Order Zoanthidae • No hard skeleton • May be tough and leathery • Shallow water forms • Encrusting forms • Some with zooxanthellae • Polyp stage only

  40. Subclass Hexacorallia Order Antipatheria Black Coral & Wire Coral Black coral Wire coral

  41. Subclass Hexacorallia Order Scleractinia “True” Stony Corals Hermatypic- reef building, zooxanthellae • Common species: • Acroporidae- table • Acroporidea- rice • Agariciidae- flat lobe, corrugated • Faviidae- crust, ocellated • Fungiidae- humpback, mushroom • Pocilloporidae- lace, antler, cauliflower • Poritidae- finger, lobe, plate

  42. “True” Stony Corals lobe finger mushroom Porites rus

  43. Subclass Alyconaria Octocorals • 8 branched tentacles surrounding the mouth • Both hard and soft forms exist • Ahermatypic- non reef building, no photosynthesis • Five Orders found in Hawaii: • Stolonifera • Pennatulacea (sea pens) • Alcyonacea (soft corals) • Telestacae (snowflake corals) • Gorgonacea (sea fans)

  44. Octocorals Sea pen

  45. Organ pipe coral