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Journal #1: KWL on Cnidarians

Journal #1: KWL on Cnidarians. PHYLUM CNIDARIA HYDRAS, JELLYFISH, SEA ANEMONES, CORAL, BOX JELLYFISH. General Information “Cnido” means nettle (stinging cell) EX: hydras , jellyfish , sea anemones , coral Found in marine & freshwater Symmetry: Radial Oral & aboral surface

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Journal #1: KWL on Cnidarians

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  1. Journal #1: KWL on Cnidarians

  2. PHYLUM CNIDARIA HYDRAS, JELLYFISH, SEA ANEMONES, CORAL, BOX JELLYFISH

  3. General Information • “Cnido” means nettle (stinging cell) • EX: hydras, jellyfish, sea anemones, coral • Found in marine & freshwater • Symmetry: Radial • Oral & aboral surface • No cephalization • Acoelomates

  4. 6. Diploblastic: two tissue layers develop from gastrula stage. • Ectoderm- develops into epidermis (skin) • Epitheliomuscular cells- for movement • Cnidocytes- for food capture/defense • Mesoglea- gelatinous middle layer containing nerve net. • Polyp- thin • Medusa- thicker • Gastroderm-develops into gut cavity • Gland cells- lubricate digestive cavity • Gastroderm- secretes digestive enzymes to digest prey.

  5. General Body Plans: Polyp & Medusa Basal disk

  6. Body Forms • Polyp • a. Cylindrical, column-like body • b. Mouth points up, surrounded by tentacles • c. Sessile, attached to surface by basal disc • d. Ex: hydra, • sea anemone

  7. Medusa • a. Bell or cup shaped body • b. Mouth points downward surrounded by tentacles. • c. Free swimming- moves by gently pulsating body • d. Ex: jellyfish

  8. III. Skeleton/support • Polyp: • have a hydrostatic skeleton-fill GVC w/water. • Gives support • Aids in movement- somersaults, inchworm • Ex: hydra, anemone • Exception- coral is sessile • 2. Medusa: • Mostly float w/currents • Can pulse bell

  9. IV. Digestion/Feeding • Eat daphnia, protists, larva, etc • Use cnidocyte containing nematocyst on tentacles to sting/stun prey • Stuff food into mouth using tentacles at oral end. (mouth on hump called hypostome) • Food is digested by gastroderm cells that line the gastrovascular cavity (GVC) • Solid Wastes leave thru mouth. • Incomplete gut b/c only 1 opening

  10. How do cnidocytes work? • The cnidocyte contains the nematocyst- fluid filled capsule with coiled, barbed thread. • Prey brush against the cnidocil which is like a trigger hair • A lid called the operculum flips open & thread containing barbs stabs/entangles prey. • Cnidocyte degenerates & a new one takes its place

  11. V. Excretion • Liquid wastes: eliminated by diffusion • Solid wastes: discharged through the mouth

  12. VI. Respiration 1. DIFFUSIONthrough cell membranes directly exposed to water.

  13. VII.Nervous System • Nerve net- layer of nerve cells in mesoglea that react to stimuli. • Most primitive form of nervous system in animal kingdom. • Jellyfish consist of cells called statocysts- senses gravity, coordinates movement

  14. VIII. Reproduction • Asexual • a. Budding- hydras, coral, sea anemones • Sexual • a. Monoecious- hermaphrodite • Spermary- makes sperm • Ovary- makes eggs • EX: hydra (polyps) • b. Dioecious- sperm & egg are produced in separate sexes. • EX: jellyfish (medusa)

  15. IX. Jellyfish Life Cycle • Sperm released by male medusa. Egg released by female. • Sperm & egg join to form zygote. • Zygote divides & differentiates into a free swimming larva called a planula. • Planula lands on a structure & begins to grow into a polyp. • Immature jellyfish grow in budding stacks called a strobila • When immature jellyfish buds break off they are called ephyra. • Ephyra grow into adult medusa jellyfish.

  16. X. Classification Craspedacusta sowerbyi (Cobb, Bartow, etc.) Class Hydrozoa * marine & fresh water * can live as single animal or colony * may be polyp or medusa * gametes made on outside of body * EX: hydra, Portuguese man-o-war

  17. Class Scyphozoa * all marine * predominant medusa stage * gametes made internally in gonads and released through the gastric pouch and finally through the mouth * called “true jellyfish” * EX: Aurelia, Lion’s mane jellyfish

  18. Lions Mane Jelly

  19. Class Anthozoa * all marine * solitary or colonial polyps * budding, monoecious or dioecious * anthozoa means “flower animal” * EX: sea anemones, coral

  20. Class Cubozoa * all marine; found in warm tropical water * medusae are cube shaped; tentacles hang down from each corner * have deadlypoison * EX: sea wasp (box jelly)

  21. XI. Economic/Environmental Significance • Part of food chain • Control animal populations • Coral & sea anemone provide habitat for other animals in coral reefs • Some corals provide medicines & jewelry • EX: Cancer, arthritis, histamines, antibiotics • 5. Coral reefs attract not only fish but tourists

  22. The stinging cell of the cnidarian is called a. Cnidocyte b. Ameobocyte c. Gland cell • Jellyfish have both a sexual & asexual stage to their life cycle. a. True b. false • Jellyfish are an example of which body form? a. Polyp b. medusa • The place where food is digested & gases are exchanged is called the a. Spongocoel b. Gastrovascular cavity c. Gland cell • The sticky adhesive base of a sea anemone is a. Spongocoel b. Gastrodermis c. Basal disc DAILY QUIZ

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