Reptiles have scales that retain moisture and lay amniotic eggs adapted for land. They live in varied habitats except very cold areas as they are ectothermic. All reptiles share scaly skin, claws, lungs, and lay amniotic eggs. Adaptations like strong skeletons and claws allow movement on land while highly developed vision aids predation and predator avoidance. Ectothermy limits habitats but basking and shade-seeking regulate temperature. Lungs and partially divided hearts aid gas exchange. Reproduction is usually oviparous but some are ovoviviparous, protecting eggs inside females.

1. The
Reptile
Body

2. Characteristics of Reptiles
 Reptiles were the first vertebrates to live on land
 Scales keep moisture inside
 Reptiles eggs DO NOT dry out on land
 Live in a variety of different habitats
 Tropical forests, desserts, oceans, rivers, and lakes
 Are NOT found in very cold regions because they are cold-blooded

3. Characteristics of Reptiles
• All reptiles share the following characteristics
– Bodies covered in scales
– Clawed toes
– Ectothermic (cold-blooded) metabolism
– Lack feathers or any form of hair
– An internal skeleton
– A heart with a partially divided ventricle
– Lungs
– Reproduce Internally
• Amniotic eggs

4. Reptile Movement and Response
 The following adaptations allow reptiles to live in
dry environments
 A strong skeleton
 Claws
 legs positioned under the body
 highly developed vision
 Since Reptiles are cold-blooded this limits their
habitat range

5. Endoskeleton
 Reptiles have a strong skeleton made of
bone
 Most reptiles have two pairs of limbs
Snakes and some lizards lack legs
Legs positioned under the body
allow reptiles to move faster and
easier on land
 Reptiles have toes with claws
Use claws for climbing and digging
Enables reptiles to run quickly
over short distances

6. Sensory Systems: Vision
 Vision is an important sense
Rely on sight to detect
predators and prey
 Eyes of reptiles are very large and
have movable eyelids
Snakes and geckos lack
movable eyelids
Reptiles that are active at
night can see very well in
the dark

7. Sensory Systems: Hearing
 Hearing is a very important
sense organ to reptiles
 Sound waves first strikes the
tympanum (ear drum) and are
then transmitted to the inner
ear
 Snakes lack a tympanum
 They detect ground vibrations
through the bones of their jaw

8. Sensory Systems: Jacobson’s Organ
 Reptiles sticks their tongues out to collect small particles
from the air
 The small particles come in contact with the Jacobson’s
Organ
 The Jacobson’s Organ is a specialized sense organ in the
roof of the mouth of many reptiles, it is sensitive to odors
 Used to “taste” the environment

9. Sensory System
 Snakes are able to detect heat
given off by warm-bloodied
prey
 Use heat sensitive pits below
each eye
 The pits allow the snake to
detect the distance and
direction of the prey

10. Body Temperature Control
 Reptiles are ectothermic
 They CANNOT heat their own body by using their metabolism
 A reptile’s body temperature is mostly determined by the
temperature of its environment
 Reptiles may bask in the sun to warm up or seek shade to cool
down
 At very low temperatures reptiles slow down and may not be
able to function

11. Respiration and Circulation
 The following adaptations allow reptiles to have
more efficient respiration and circulation
 1. Lungs with a large surface area
 2. A heart that is almost completely divided into
four chambers

12. Reptile Lungs
 Reptile lungs have many internal folds, which
gives the lungs a large surface area for oxygen
exchange
 Strong muscles in the rib cage allow air to move in
and out of the lungs quickly, which increases lung
efficiency

14. Reptile Heart
 The septum partly divides the ventricle into right
and left halves
 Enables a much better, but still incomplete,
separation of oxygen-rich and oxygen-poor blood
 Oxygen is delivered to the body cells more
efficiently in reptiles than in amphibians

15. Reptile Reproduction
 Reptile reproduction occurs through internal fertilization
 Many reptiles are oviparous: the young hatch from eggs that
are laid outside the mother’s body.
 Some snakes are lizards are ovoviviparous: fertilized eggs
remain inside the female’s body for a long time and hatch
inside the female
 This protects the eggs from predators
 Most reptiles DO NOT care for their young
 Alligators and crocodiles are an exception

16. Amniotic Eggs
 An amniotic egg contains both a water supply and
food supply
 Amniotic eggs are key to a reptile’s success as a
terrestrial animal
 They are watertight

17. Amniotic Egg Structure
 The shell and albumen protects
and cushions the embryo
 Also a source of nutrients
 There are four membranes in the
amniotic egg
 1. Amnion- cushions the embryo
 2. Yolk Sac- contains the embryo’s
main food supply, blood vessels
attach here
 3. Allantois- stores waste and is the
embryo’s organ for gas exchange
 4. Chorion- allows oxygen to enter
the egg and carbon dioxide to leave
the egg