1. The Reptilian Body
Section 34.1

2. 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

3. 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

4. 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

5. 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

6. 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