BIOL 305 Lecture Notes - Flatworm, Statocyst, Cestoda

• School: McGill University
• Department: Biology (Sci)
• Course: BIOL 305
• Professor: Virginie Millien

Document Summary

Platyhelminthes: naked epidermis, have rhapdites: may be protective structures, or may be for hormonal excretion, the internal area is fill filled with mesenchyme (not cellular, but with) w/ wandering amebocytes, predator, inverts the pharynx to eal with larger prey. 22/1/14: eyes: photoreceptor at the front end (other platyhelminthes may have chemoreceptors an statocysts, central nervous system: has nerve cords extending down the body mostly ventral and a nerve plexus at the front end, no circulatory system: this is why they are flat (aid diffusion, development: see slide no gastrulation because everything"s happening in an enclosed space. 10cm in length: may still move through ciliated epidermis (smaller), but larger ones move/swim with a flapping of the folds of the body wall ( marginal ruffling , degree of cephalization that exceeds other platyhelminthes, pseudotenticles: sensory organs, simple eyes w/o lens, so no images, but photoreceptive, pharynx that is invertible with lacy branching gut structures.