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Chapter 34/35 : Worms I. Body Positions Dorsal (Back) Posterior (Rear) Anterior (Head) Ventral (Belly) *Bilateral symmetry – cut down middle and both halves the same II. Phylum Platyhelminthes – flat worm 1.) Planarian – aquatic A. 2 eyespots (sense light) Hermaphrodite (male & female) Regenerate – regrow missing parts Scavenger II. Phylum : Platyhelminthes ○ 2.) Fluke Parasite Thick cuticle & suckers Hermaphrodite Common in Orient, Cuba Life cycle with a snail II. Phylum : Platyhelminthes ○ 3.) Tapeworm Head contains suckers scolex Proglottid – each contains sex organs (hermaphrodite) Passes through feces eaten by pigs or cows Causes organisms to lose nutrients, weight, weakness II. Phylum : Nematoda Nematoda – round worm 1.) Ascaris B. Pigs, horses, humans through dirt or contaminated food 2.) Hookworms – bore into feet Common in south and tropics Cause anemia and slows growth II. Phylum: Nematoda 3.) Trichina – found in contaminated pork 4.) Pin Worms – found in soil Phylum : Annelida – segmented worms, earthworm, leech C. II. Phylum : Annelida ○ 1.) Characteristics of Annelida Soil or no soil Not parasite Called tube within a tube Fertilize and aerate soil Hermaphrodites II. Phylum: Annelida ○ 2.) External Parts Prostomium – lip Clitellum – band of reproduction segments – 32-37 Setae – bristles on ventral surface used for clinging II. Phylum : Annelida ○ 3.) Digestive System Pharynx – sucks soil To Esophagus then to crop (stores food) To Gizzard (grinds food) Through Intestine and out anus II. Phylum : Annelida ○ 4.) Circulatory System Dorsal Blood Vessel – blood flows through anterior end Ventral Blood Vessel – blood from posterior end Aortic Arches – 5 pairs-like heart – pumps blood Closed Circulatory System – blood remains in tubes II. Phylum : Annelida ○ 5.) Respiration & Excercretion Absorb O2 and releases CO2 through skin. Mucus from skin helps moisten air for easier respiration. Also slides through soil better. Waste excreted by anus and nephridia (holes on segments that act like kidneys- excrete liquid waste) II. Phylum : Annelida ○ 6.) Nervous System Ventral nerve cord (white) Sensitive to sound and light Brain Tissue II. Phylum : Annelida ○ 7.) Reproduction Hermaphrodite but eggs must be fertilized by another worm *Sperm made in testes and stored in seminal vessicles. Received sperm is stored in the Seminal Recepticles. * During Reproduction * Worms line up upside-down. Eggs Released into slime ring around clitellum. Sperm released to fertilize eggs. Slime ring slips off to form protective cocoon for developing young.