The Reptilian Body Section 34.1

Key Characteristics Strong, bony skeleton, including toes and claws Ectothermic metabolism Dry, scaly, almost watertight skin Amniotic eggs, almost watertight Respiration through well-developed lungs Heart ventricle partially separated by a septum Internal fertilization of eggs

Temperature Regulation Reptiles are ectotherms They regulate their body temperature by behavior – basking in sunlight or seeking shade At colder outside temperatures they become sluggish This limits their geographical range

Water Retention Watertight skin: Light, flexible, overlapping scales Watertight eggs: Internal fertilization Tough, leathery shell Amniotic egg which contains both water and food for the embryo

Respiration No cutaneous respiration due to scaly skin Lungs have many internal folds to increase surface area and therefore efficiency Strong rib muscles aid in breathing The heart has a right and left atrium and a partially divided ventricle which helps to separate high O2 blood from low O2 blood

Reproduction Fertilization occurs within the female’s body Most reptiles are oviparous – the young hatch from eggs laid outside the mother’s body; only a few species care for their young Some reptiles are ovoviviparous – the eggs are kept inside the mother’s body until hatching; this reduces the risk from predators