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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 Symmetry: Radial Found in marine & freshwater

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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 • Symmetry: Radial • Found in marine & freshwater • Diploblastic: two tissue layers • a. Ectoderm- develops into epidermis (skin) • b. Endoderm- develops into gastrodermis which lines the “stomach” (gut cavity)

  4. General Body Plans: Polyp & Medusa Basal disk

  5. Body Forms • Polyp • a. Cylindrical, column-like body • b. Mouth points up, surrounded by tentacles • c. Sessile, attached to surface by basal disc

  6. Medusa • a. Bell or cup shaped body • b. Mouth points downward surrounded by tentacles. • c. Free swimming- moves by gently pulsating body

  7. III. Digestion/Feeding • Use cnidocyte containing nematocyst on tentacles to sting/stun prey • Eat daphnia, protists, larva, etc • Stuff food into mouth using tentacles at oral end. • Food is digested by special cells in the gastrodermis that line the gastrovascular cavity. • Wastes leave thru mouth.

  8. The cnidocyte contains the nematocyst- fluid filled capsule with coiled thread. • Prey trigger the cnidocil (trigger hair), operculum (lid) opens & thread containing barbs stabs/entangles prey. • Cnidocyte degenerates & a new one takes its place

  9. IV. Respiration 1. DIFFUSIONthrough cell membranes directly exposed to water.

  10. V. Skeleton/support • Hydra & sea anemones have a hydrostatic skeleton- fill gastrovascular cavity w/water. Gives support • 2. Aids in movement- somersaults, inchworm • Jellyfish mostly float w/currents • Coral are sessile

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

  12. VII. Excretion 1. Through mouth or directly into water from cells.

  13. VIII. Reproduction • Asexual • a. Budding- hydras, coral, sea anemones • Sexual • a. Monoecious- hermaphrodite, “one house” • EX: hydra • b. Dioecious- sperm & egg are produced in separate sexes. • EX: jellyfish

  14. IX. Jellyfish Life Cycle • Sperm released by male medusa. Egg released by female. • Sperm & egg join to form zygote. • Zygote goes through several cell divisions & forms a hollow ball of cells called a blastula. • Blastula eventually forms into a free swimming larva called a planula. • Planula lands on a structure & begins to grow into a polyp. • Polyp buds break off & grow into free swimming medusa.

  15. 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

  16. Class Scyphozoa * all marine * predominant medusa stage * gametes made internally & released thru mouth * called “true jellyfish” * EX: Aurelia

  17. Lions Mane Jelly

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

  19. Class Cubozoa * all marine; found in warm tropical water * medusae are cube shaped; tentacles hang down from each corner * have deadly poison (each tentacle with 500,000 cnidocytes; deaths in Japan, Australia, Malaysia, Gulf of Mexico; suffer severe physical and psychological symptoms ) * EX: sea wasp (box jelly)

  20. XI. Economic/Environmental Significance • Part of food chain • Control animal populations • Coral provide habitat for other animals in coral reefs • Some corals provide medicines & jewelry • EX: Cancer, arthritis, histamines, antibiotics

  21. 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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