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Journal #1: KWL on Cnidarians K- What do you know? W- What do you want to know? L- What have you learned? PHYLUM CNIDARIA HYDRAS, JELLYFISH, SEA ANEMONES, CORAL, BOX JELLYFISH I. General Information 1. “Cnido” means nettle (stinging cell) 2. EX: hydras, jellyfish, sea anemones, coral 3. Symmetry: Radial 4. Found in marine & freshwater 5. Diploblastic: two tissue layers a. Ectodermdevelops into epidermis (skin) b. Endodermdevelops into gastrodermis which lines the “stomach” (gut cavity) General Body Plans: Basal disk Polyp & Medusa II. Body Forms 1. Polyp a. Cylindrical, column-like body b. Mouth points up, surrounded by tentacles c. Sessile, attached to surface by basal disc 2.Medusa a. Bell or cup shaped body b. Mouth points downward surrounded by tentacles. c. Free swimmingmoves by gently pulsating body III. Digestion/Feeding 1. Use cnidocyte containing nematocyst on tentacles to sting/stun prey 2. Eat daphnia, protists, larva, etc 3. Stuff food into mouth using tentacles at oral end. 4. Food is digested by special cells in the gastrodermis that line the gastrovascular cavity. 5. Wastes leave thru mouth. 1. The cnidocyte contains the nematocyst- fluid filled capsule with coiled thread. 2. Prey trigger the cnidocil (trigger hair), operculum (lid) opens & thread containing barbs stabs/entangles prey. 3. Cnidocyte degenerates & a new one takes its place IV. Respiration 1. DIFFUSION through cell membranes directly exposed to water. V. Skeleton/support 1. Hydra & sea anemones have a hydrostatic skeleton- fill gastrovascular cavity w/water. Gives support 2. Aids in movementsomersaults, inchworm 3. Jellyfish mostly float w/currents 4. Coral are sessile VI.Nervous System 1. Nerve net- layer of nerve cells in mesogleagelatinous middle layer- that react to stimuli. 2. Most primitive form of nervous system in animal kingdom. 3. Jellyfish consist of cells called statocystssenses gravity, coordinates movement VII. Excretion 1. Through mouth or directly into water from cells. VIII. Reproduction 1. Asexual a. Budding- hydras, coral, sea anemones 2. Sexual a. Monoecioushermaphrodite, “one house” EX: hydra b. Dioecious- sperm & egg are produced in separate sexes. EX: jellyfish IX. Jellyfish Life Cycle 1. Sperm released by male medusa. Egg released by female. 2. Sperm & egg join to form zygote. 3. Zygote goes through several cell divisions & forms a hollow ball of cells called a blastula. 4. Blastula eventually forms into a free swimming larva called a planula. 5. Planula lands on a structure & begins to grow into a polyp. 6. Polyp buds break off & grow into free swimming medusa. 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 Class Scyphozoa * all marine * predominant medusa stage * gametes made internally & released thru mouth * called “true jellyfish” * EX: Aurelia Lions Mane Jelly Class Anthozoa * all marine * solitary or colonial polyps * budding or can be monoecious or dioecious * anthozoa means “flower animal” * EX: sea anemones, coral 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) XI. Economic/Environmental Significance 1. Part of food chain 2. Control animal populations 3. Coral provide habitat for other animals in coral reefs 4. Some corals provide medicines & jewelry EX: Cancer, arthritis, histamines, antibiotics 1. The stinging cell of the cnidarian is called a. Cnidocyte b. Ameobocyte c. Gland cell 2. Jellyfish have both a sexual & asexual stage to their life cycle. a. True b. false 3. Jellyfish are an example of which body form? a. Polyp b. medusa 4. The place where food is digested & gases are exchanged is called the a. Spongocoel b. Gastrovascular cavity c. Gland cell 5. The sticky adhesive base of a sea anemone is a. Spongocoel b. Gastrodermis c. Basal disc DAILY QUIZ