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Reptiles
Section 31.1
Animal Classification
Invertebrates
Sponges
Cnidarians
Worms
Mollusks
Arthropods
Echinoderms
Animals
(cold-blooded)
Fishes
Amphibians
Reptiles
Endotherms
Birds
Mammals
Ectotherms
Vertebrates
(warm-blooded)
What is a Reptile?
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Class Reptilia – snakes, turtles, alligators,
and lizards
Evolutionary advantages reptiles have over
amphibians
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Claws
Dry skin (scales)
Scaly Skin
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Unlike the moist, thin skin of amphibians,
reptiles have a dry, thick skin covered with
scales
Scaly skin prevents the loss of body moisture
and provides additional protection from
predators
Scaly Skin
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Because of their thick skin, reptiles are
dependent on lungs as their primary organ of
gas exchange
Desert Horned Lizard
Reproduction
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Most reptiles reproduce by laying eggs on
land
Some snakes give live birth to well-developed
young
Sea turtle eggs
Gartner snake giving birth
Reproduction
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All reptiles have internal fertilization
Snakes and lizards have hemipenes (plural)
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Hemipenis (singular) – structure used to inject
sperm into a female
Cloaca – opening where the hemipenes is
inserted; waste also exits the cloaca
Ectotherms
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Reptiles do not inhabit extremely cold regions
Many species of reptiles become dormant
during cold periods in moderately cold
environments (northern United States)
Sense Organs
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Pit organs – heat-sensitive areas that enable
snakes to detect air temperature brought by
the presence of warm-blooded animals
Sense Organs
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The tongue is used for smelling
Jacobson’s organ – a pitlike sense organ on
the roof of the mouth that picks up and
analyzes airborne chemicals
Turtles
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The dorsal part of the shell is the carapace,
and the ventral part is the plastron
The vertebrae and expanded ribs of turtles
are fused to the inside of the carapace
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Turtles
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Tortoises
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Aquatic
Eat insects and worms
(some eat birds)
Have claws
Webbed feet
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Can live up to 60 years
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Terrestrial
Eat fruits and insects
Do not have claws
Feet are not webbed;
they’re round and stumpy
Can live up to 150 years
Crocodiles
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Crocodiles
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Long, slender, V-shaped
snouts,
Light olive brown
coloration
Found in saltwater and
estuaries

Estuary – a mixture of
freshwater and saltwater
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Alligators

Short, broad, U-shaped
snouts
Blackish coloration
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Found in freshwater
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Snakes and Lizards
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Most lizards have four limbs
Snakes have no limbs and lack the bones to
support limbs

Exception are pythons and boas which retain
bones of the pelvis
The claw is known as a spur
Lizards and Snakes
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Some snakes even swim and climb trees
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Have ridges on its belly used for gripping
(like tire treads gripping the road)
Lizards and Snakes
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Snakes usually kill their prey in one of three
ways

1. Constriction – snakes wrap themselves around
their prey
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Examples: boas, pythons, and anacondas
Boa
Lizards and Snakes
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2. Venom – These snakes use poison to paralyze
or kill their prey
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Rattlesnakes, cobras, and vipers
Lizards and Snakes
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3. Non-poisonous and non-constricting snakes get
their food by grabbing it with their mouths and
swallowing it whole