BIOL 111 Lecture 18: BIOL 111 – Lecture 18 – Reptiles

• School: McGill University
• Department: Biology
• Course: BIOL 111
• Professor: Rudiger Krahe

Document Summary

Lecture date/time: nov 10th, 2015 / 10:35-11:25 am. Reptiles are a paraphyletic group, include birds. Must conserve water now even their reproduction is outside of the water. They produce a special nitrogenous waste (uric acid) Skin is waterproofed by keratin (= fibrous protein forming the main structural constituent of hair, feathers, hoofs, claws, horns, etc. ) Breathe via lungs only (no gills, not through skin (amphibians also use gas exchange through their skin) Stability to egg, protect against desiccation (= extreme dryness), is water-tight fertilization must happen internally, before shell is formed. Heart: fish = simple circuit, 2 chambers; amphibians = 2 circuits, 3 chambers (inefficiency of mixed blood in the ventricle) Reptiles (turtles, snakes, lizards) : 5-chambered heart, more separated heart between lung and systemic circuits, but still a bit of mixing. Reptiles (crocodilians) : fully divided ventricle = 4 chambers, but still have the shunted aorta crocodiles drag prey underwater.