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I. Simple Invertebrates A. Characteristics: 1. All animals without backbones. 2. Have external skeletons (exoskeletons). 3. Includes 97% of all animals. 4. Sexual & asexual reproduction. 5. Some are hermaphrodites – posses both male & female sex organs. II. Invertebrate Phyla A. Phylum Porifera Ex. sponge 1. Characteristics a. Sessile – Adults are permanently attached to a surface & do not move. b. Filter feeders of plankton. c. Can regenerate missing body parts. d. Live in fresh & salt H2O. 2. Body Parts: See Handout 1. Ostia – tiny openings to filter. 2. Collar cells - flagellated cells to trap food. 3. Amoebocytes - carry food to other cells; help in reproduction 4. Spongin - flexible protein skeleton. 5. Spicules - tiny needles of silica or calcium carbonate that make up the skeleton. 3. Reproduction a. Asexual •Budding – growth of new organism on body of parent; breaks off to form new sponge. •Regeneration – regrow missing body parts. •Gemmules- encasing produced when conditions are bad. b. Sexual Sponges are hermaphrodites. They produce both egg & sperm in the same body, but at different times to prevent self-fertilization. B. Phylum Cnidaria Means “stinging animal.” Ex. - Jellyfish, hydra, coral, & sea anemone. Coral Reef 1. Characteristics: a. Have radial symmetry. b. Live as individuals or in colonies. c. Have tentacles with “stinging cells”. d. Have 2 body forms: 1) polyps - vase-shaped body. Ex. - hydra 2) medusas - umbrellashaped body. Ex. – jellyfish e. Live in fresh & salt H2O. 2. Body Parts: See Handout 3. Reproduction a. Sexual - Sperm fertilizes egg, then zygote develops into a larva, then into a polyp. b. Asexual - Polyp (formed in sexual reproduction), forms buds that become tiny medusa. Sea anemone II. Invertebrate Phyla Continued: C. Phylum Platyhelminthes Flatworms •Ex. - planaria, tapeworms, & liver flukes. Planarian 1. Characteristics: a. Have bilateral symmetry. b. Have a dorsal & ventral surface. c. Live in fresh & salt water. d. Planarians are freeliving scavengers. e. Tapeworms & flukes are parasites (require a host). 2. Body Parts: See Handout Planaria Tapeworm Deer Liver Fluke 3. Reproduction: a. Asexual - binary fission b. Sexual – by internal fertilization (they are hermaphrodites) Tapeworm Infection D. Phylum Nematoda Roundworms •Ex. – hookworms, pinworms, Ascaris, & Trichina Ascaris 1. Characteristics: a. Have anterior & posterior ends. b. Found everywhere. c. Are dioecious - have male & female gonads, but not both. 2. Body Parts: a. Mouth at anterior end, anus at posterior end. b. Muscles are used for locomotion. 3. Reproduction: a. Sexual 4. Parasitic Diseases: a. Trichinosis caused by eating raw pork containing the Trichina worm. b. Hookworm enters feet through the skin (common in the U.S.). Hookworm 3. Pinworm - infestation is common in children in daycare settings when they eat something that has come in contact with contaminated soil. Pinworm E. Phylum Annelida Annelida means “little rings.” Segmented Worms •Ex. – earthworm & leech 1. Characteristics: a. Have bilateral symmetry. b. Live in marine & freshwater & in soil. c. Have well-developed organ systems. d. Have a coelum – fluid-filled body cavity. 2. Earthworm Body Organs & Systems: See Handout a. Digestive System: 1. mouth, pharynx, esophagus, crop, gizzard, intestine, & anus b. Closed Circulatory System: 1. 5 aortic arches, dorsal & ventral blood vessels, & blood (colorless) c. Excretory System: 1. nephridia & anus d. Nervous System: 1. brain, ventral nerve cord, & ganglia e. Muscular System: 1. lengthwise (longitudinal) & circular muscles. f. Reproductive System: 1. clitellum, ovaries, seminal vesicles, & seminal receptacle g. Respiratory System: NO ORGANS oxygen diffuses through the skin to the blood vessels. 2. Reproduction: Sexual – hermaphrodites, but they do not fertilize their own eggs.