Reptiles/ Amniotes Ch. 26
Phylum: Chordata
Subphylum:Vertebrata
Order
Testudines Rhynchocephaili
a
Common Turtles
example and
tortoises
Tuataras-found only
in New Zealand
Squamata Crocodilia
Lizards,
Alligators
snakes,
and
and worm
crocodiles
lizards
Different Orders of Reptiles : small group work
Order: Chelonia, Order Rynchocephalia,
Order : Squamata, Order Crocodilia
 Examples
 Digestion
 Respiration
 Skin
 Skeletal system
 Circulatory system
 Movement
 Reproduction methods
 Unique Characteristics for that group
Digestive System
Complete
Carnivorous
Have a secondary palate that allows them to
breathe while their mouth is full.
 Snakes :the upper and lower jaws are moveable
on the skull and can move independently.
Like the fish and amphibians, reptiles have a
cloaca.
Respiratory system:
Adult-lungs
Lack a diaphragm so inspiration
and expiration are controlled by
contraction of the thoracic (chest)
muscles.
NO cutaneous respiration
Negative pressure breathing
skin
Thick and dry
Covered with epidermal scales
Scales contain keratin (a protein
that helps prevent water loss)
External Anatomy and Skeleton
Ossified (hardened) to support locomotion
on land
Snakes and lizards have the temporal arch
on the skull reduced or absent
Turtles have a dorsal carapace (shell) to
which the ribs are fused
Circulation:
Double looped; systemic=to the
body pulmonary= to the lungs
Three chambered heart: 2 atria and
1 ventricle
Crocodiles have a 4 chambered
heart
Temperature Regulation:
Ectothermic
Often bask in the sun
Nervous System
Cerebrum: slightly larger than amphibians, associated
with improved sense of smell
Cerebellum with optic lobes: slightly larger than
amphibians, associated with improved sight and motor
coordination
Medulla oblongata: regulates heart rate and respiration
Sight: most have binocular vision which allows for depth
perception, Tuataras have an additional parietal eye (a
photoreceptor) located mid-dorsally on the head.
Nervous System- continued
Nictitating membrane to protect eye
Hearing: not their most developed
sense
Smell: have an olfactory receptor in
the mouth used to sample airborne
chemicals called Jacobson’s organ.
Excretory System
Have metanephric kidneys
(contains many more bloodfiltering units called nephrons).
Nitrogenous waste in the form of
uric acid (paste-like).
Reproductive System
 Dioecious and oviparous (lay eggs)
 Internal fertilization: Copulatory organs
 Lay amniotic eggs
Differentiates reptiles, birds and mammals from other vertebrates
have extraembryonic membranes:
amnion-fluid filled cavity for cushioning the embryo
chorion-gas exchange surface resistance to water loss
allantois-metabolic waste stored
yolk sac-food
shell-protection
Amniotic Egg= has food supply for
embryo, laid on dry land
4 main parts to Amniotic Egg
Amniotes- Reptiles, Birds, and Mammals
 Allantois- respiration/ excretory/ storage for excretory
 Yolk sac- nutrition
 Amnion- protection
 Shell- protection
Skull subclasses
lizards, snakes, crocodiles and tuataras, have upper and lower openings in the
temporal region (yellow) of the skull, shows relationship to birds.
:
 Diapsid:
Anapsid: turtles, lack openings in the temporal region (yellow) of the skull.
.
 Synapsid: alligators,
have a single opening in the
temporal region of the skull, shows relationship to
mammals