BIOL 101 Lecture Notes - Lecture 12: Model Organism, Lophophore, Moulting

• School: McGill University
• Department: Biology
• Course: BIOL 101
• Professor: Rudiger Krahe

Document Summary

Rabbits have cecum, earthworms have gizzard, cows have 4 chamber stomach incl. rumen. Acts as storage reservoir for gametes, waste, etc. Mesoderm lines the entire cavity as a peritoneum. Ciliated (for locomotion & feeding) free-living larval form. External covering secreted by epidermis, shed to grow. Growth occurs in steps, mass increases continuously. Allows diffusion of gases (needs moist habitat) Largest nematode: 9m long (in placenta of sperm whales) Hookworm, common in tropics, occurs in dogs & humans. Major model organism of geneticists, developmental biologists & neurobiologists. Important part of food web of soil. Major evolutionary advance seen in many animal groups. Segments are similar but can be modified. Each segment has longitudinal & circular muscles, coelomic space (hydrostatic skeleton) Longitudinal muscles contract, posterior setae anchor release. Permits development of thicker body (free of diffusion limit) Many have eyes, tentacles & setae (in name)