BIOL 111 Lecture Notes - Yolk Sac, Osmotic Concentration, Ovoviviparity

• School: McGill University
• Department: Biology (Sci)
• Course: BIOL 111
• Professor: Irene Gregory- Eaves

Document Summary

3 unique characteristics: dorsal hollow nerve cord, notochord: supportive rod internally (highly reduced in vertebrates, replaced by spine, post-anal tail. Other characteristics: pharyngeal slits: found in chordates but not unique to them: seen first in deuterostomes, hollow dorsal nerve cord and segmentation is formed by neurulation, central heart, reduced segmentation, segmented musculature. In all vertebrates, ancestral trait in deuterostomes. In vertebrates: are supported by arches: what become jaws and are important for gas exchange. For respiration in vertebrates: water coming in mouth passes through slits. O2 and co2 can be exchanged across a respiratory surface = gills. Gills: bars in between the slits = gill arches. Gill filaments on gill arches: respiratory exchange takes place. In boney fishes: 4 pairs of gill arches. Gill raker: strained food, prevents food from exiting mouth through. = thin, vascularized, high surface area, moist, maintain partial pressure.