Reptiles
Section
31-1
Section 31-1 Learning Targets
• Describe the characteristics of
reptiles
• Explain how reptiles are
adapted to life on land
• Identify the four living orders
of reptiles
Classification
• Kingdom: Animalia
– Phylum: Chordata
•Subphylum: Vertebrata
–Class Reptilia
What is a Reptile?
•
•
•
•
•
Vertebrate
Dry, scaly skin
Breathe with lungs
Terrestrial eggs
Internal fertilization
Form & Function
• BODY TEMP CONTROL
– ECTOTHERMS: rely on external
environment to control temp
• Lay in sun to warm up, move in shade to cool
down
• Feeding
– Reptiles can be herbivores or carnivores
– Most are carnivores that eat insects
Form & Function
• RESPIRATION:
– LUNGS: spongy, so more gas exchange
than amphibians
• NO gas exchange thru skin
– Muscles expand rib cage to inhale
– Collapse the cavity to exhale
Form & Function
• CIRCULATION:
– Efficient Double-Loop
• One loop brings blood to and from the lungs
• Other loop brings blood to and from the
rest of the body
– 2 atria; 1 ventricle (partially divided)
– Alligators have 4-chambered heart
• EXCRETION:
– Kidneys produce urine
• Nitrogenous wastes are excreted in
the form of ammonia or uric acid
• Aquatic reptiles usually excrete
ammonia that has been diluted with
water
– Terrestrial reptiles usually
excrete uric acid as crystals
(conserves H20)
Form & Function
• RESPONSE:
– Active during day; complex eyes; see color well
– Detect smell and chemicals on roof of mouth
• EX: snake flick tongue to bring chemicals into mouth
• Some snakes can even detect the body heat of their prey!
• REPRODUCTION
– All reptiles reproduce by INTERNAL
FERTILIZATION
• Male deposits sperm inside body of female
– OVIPAROUS (most)
• Lay eggs that develop outside of body
– Ovoviviparous (some snakes and lizards)
Reproduction, cont’d.
• Unlike amphibian eggs, which need to
develop in water, the shell and
membranes protect the reptilian embryo
from drying out
– Reptiles use an AMNIOTIC EGG (hard
shell)
• Four membranes surround the embryo inside the
shell:
– CHORION
– YOLK SAC: serves as food supply
– AMNION: fluid-filed sac surrounds / cushions
embryo
– ALANTOIS
Groups of
Reptiles
4 Orders of Reptiles
• Order Squamata ( Lizards and Snakes)
• Order Crocodilia (alligators and
crocodiles)
• Order Testudines (Turtles and
Tortoises)
• Order Sphenodonta (Tuatara)
Order Squamata
• Snakes and Lizards
– Evidence suggests that snakes evolved from
lizards that burrowed
– Snakes retain small leg bones even though they
have no legs
• Types of Lizards
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–
–
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Komodo Dragon
Gecko
Chameleon
Bearded Dragon
• Types of Snakes
– Cobra
– Rattlesnake
– Copperhead
Frilled Lizard
Gila Monster
Horned Lizard
Cobras and Coral Snakes
• Cobras and Coral snakes
– Inject a neurotoxin that causes paralysis
and breathing difficulties
Coral Snake
Cobra
Sea Snakes
• Spend most of their life
underwater
• Tails are shaped like a paddle to
help them swim
Adders and Vipers
• Adders and vipers
– Very venomous
Rattlesnakes
• Rattlesnakes and water moccasins
(cottonmouths)
– Inject a hemotoxin which causes destruction
of the blood and tissue
– The area of the bite becomes swollen and
dark.
Copperheads
Order Crocodilia
• Crocodiles, Alligators, Caimans and
Gavials
• Only reptile group that takes care of
their young (very protective of young)
• Adapted to stealth hunting - eyes and
nostrils are above the head, so the body
can remain submerged
– They attack when animals (or humans) come
to the water shore to drink
• Crocodiles
– Pointier snout and teeth stick out
– Live in fresh or salt water in Africa, India
and Southeast Asia
• Alligators
– Snout that is more rounded and teeth fit
into a socket
– Live only in fresh water and are almost
exclusively in North and South America
Crocodiles
Alligators
Order Testudines
• Turtles and Tortoises
– Characterized by a shell that is fused to the turtle's
spine
• It cannot be removed, nor can a turtle crawl out of it.
– The top of the shell is the carapace, the bottom
of the shell is the plastron.
• Turtles - generally live in water
– Sea turtles migrate long distances to lay their eggs
at the same beach they were born at.
• Tortoises - live on land and have rounded bodies
Order Sphenodonta
• Tuatara only surviving member
• Known as a "living fossil"
– They have survived unchanged for 150
million years
• Has a “third eye” above brain can sense
the level of sunlight (function unknown)
• Only lives in New Zealand and is in
danger of becoming extinct
• Tuataras have distinctive head spikes
That’s All
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