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Phylum Cnidaria

Phylum Cnidaria. All contain nematocysts- stinging structures. Cnidarians. Jellies, Anemones, Corals Dimorphism : Two body shapes during life cycle. ( Polyp & Medusa ) Gastrovascular cavity (digestive) Carnivores Primitive nerve net Two distinct tissue layers: Epidermis & Gastrodermis

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Phylum Cnidaria

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  1. Phylum Cnidaria All contain nematocysts-stinging structures

  2. Cnidarians • Jellies, Anemones, Corals • Dimorphism: Two body shapes during life cycle. (Polyp & Medusa) • Gastrovascular cavity (digestive) • Carnivores • Primitive nerve net • Two distinct tissue layers: Epidermis & Gastrodermis • Cnidocyte (Stinging cells) in tentacles • Radial Symmetry

  3. Tentacles Mesoglea Gastrovascular cavity Mouth/anus Mouth/anus Gastrovascularcavity Tentacles  The Polyp and Medusa Stages Epidermis Mesoglea Gastroderm Polyp Medusa

  4. Feeding • Paralyze prey and pulls into mouthgastrovascular cavity • Undigested materials passed out through mouth/anus

  5. Respiration, Circulation, Excretion • Diffusion through body walls • Nerve net-network of nerve cells to detect stimuli • Statocysts to determine gravity direction • Ocelli as eyespots to detect light Response

  6. Movement • Hydrostatic skeleton-muscles w/ water enable movement Body contracts to force water out, moving jellyfish in opposite direction.

  7. Reproduction and Life cycle • Most cnidarians reproduce both sexually and asexually. • External fertilization

  8. Jellyfish Life Cycle Female medusa(2N) MEIOSIS Fertilization occurs in the open water, producing many diploid zygotes. Egg (N) FERTILIZATION Adult medusas reproduce sexually by releasing gametes intothe water. Sperm (N) Each zygote grows into a ciliated larva. The larva eventually attaches to a hard surface and develops into a polyp. Zygote (2N) Male medusa(2N) Youngmedusa Swimming larva Polyp The polypbuds to release young medusas. Buddingpolyp Haploid Diploid

  9. Classes of Cnidaria • Hydrozoa (Serpent Animals) • Scyphozoa (Cup Animals) • Anthozoa (Flower Animals)

  10. Class Hydrozoa • Both body forms: polyp and medusa • Reproduce sexually as medusas. • Example: Portuguese Man Of War

  11. Class Scyphozoa • True jellies • Medusa form during most of its life cycle. • Lions Mane is the most common in L.I.S. • Butter fish lives in its tentacles.

  12. Moon Jelly • Free swimming • Up to 30 cm wide • Found in intertidal zone • Found in L.I.S. (Also in the tanks of Maritime Aquarium)

  13. Sea Wasp (another scyphozoan ex.) • Known as box jellyfish • Most powerful venom in the world • Lives in Australia • Can be up to 60 meters in length

  14. Class Anthozoa • They are individual or colonies of polyps found in coastal waters. • No medusa stage. • Examples: Sea anemones,Hard corals, sea fans

  15. Northern Red Anemone • 7.5 cm high, 12.5 cm wide • Attach to rocks under rockweed. • Found in subtidal zones

  16. Striped Anemone • 2 cm high .5 cm wide • Found on lower rocks on sheltered shores. • Can tolerate reduced salinity.

  17. Sea fans

  18. Hard corals

  19. Phylum Ctenophora • Ctenophores • Common name: Comb jellies • Contain eight rows of comb plates made of cilia used for locomotion (ciliary combs) • Bioluminescent • No stinging cells • They feed on plankton

  20. Comb Jellies

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