BIOL 202 Midterm: Phylum-Platyhelminthes

• School: Queen's University
• Department: Biology
• Course: BIOL 202
• Professor: Laurene M Ratcliffe

Document Summary

Pedal locomotion (muscular: waves across the body. Subepidermal nerve plexus resembles nerve net of cnidarians. Photoreceptors: two simple eyespots called ocelli (orient animal in direction of light, provide oxygen to tissues at adequate pressure and remove waste. Pharynx functions as ingestive organ, free end of tube lies in a pharyngeal sheath and can project out of mouth when feeding. Pharyngeal glands secrete enzymes that help break down food into smaller units that can be taken into the pharynx. In the digestive cavity, phagocytic cells engulf small units of food and digestion is completed in intracellular vesicles. Class trematoda: endoparasites with complex life cycle (flukes) Oral sucker used for locomotion/attaching to host. Pair of ganglia in head region: two or three pairs of nerve chords run down length of body. Digestive tract includes a mouth and pharynx. Posterior to pharynx, the digestive tract divides into two blind-ending, variously branched pouches called cecae. Suckers, hooks, lives inside vertebrate digestive system.