the reptilian body section 34.1. key characteristics 1. strong, bony skeleton, including toes and...

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The Reptilian Body SECTION 34.1

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The Reptilian BodySECTION 34.1

Key Characteristics

1. Strong, bony skeleton, including toes and claws

2. Ectothermic metabolism

3. Dry, scaly, almost watertight skin

4. Amniotic eggs, almost watertight

5. Respiration through well-developed lungs

6. Heart ventricle partially separated by a septum

7. 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 fertilizationTough, 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