Download The Reptile Body

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 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
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
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 warmbloodied 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
Review Questions
• 1. Identify seven characteristics of reptiles
• 2. Describe how being ectothermic influences a
reptile’s lifestyle
• 3. Explain how reptiles meet their need for
oxygen
• 4. Summarize how the amniotic egg allows
reptiles to live on land
• 5. Do you think a reptile that cares for its young
lays more or fewer eggs than a reptile that
doesn’t care for its young? Explain