The Reptile Body

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, des\serts, oceans, rivers, and lakes Are NOT found in very cold regions because they are cold-blooded

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

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

Endoskeleton Reptiles have a strong skeleton made of

bone Most reptiles have two pairs of limbs

Snakes and some lizards lack legsLegs positioned under the body

allow reptiles to move faster and easier on land

Reptiles have toes with clawsUse claws for climbing and digging Enables reptiles to run quickly

over short distances

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 eyelidsSnakes and geckos lack

movable eyelidsReptiles that are active at

night can see very well in the dark

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

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

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

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

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

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

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

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

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

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