Animals
Crocodiles and alligators
Dinosaurs
Lizards
SnakesRePTiLes437
SCALeS
A reptile’s scaly skin provides good
protection against predators and
stops the animal from drying out.
The arrangement of the scales helps
scientists identify species. Some
reptiles, such as chameleons, have
special cells in the skin. These cells
make the colored pigments
inside the skin
expand or
contract.
This is
how the
chameleon
changes its
color, for
camouflage.TemperATure reguLATion
We often describe reptiles
as cold-blooded, but this is
not strictly true. reptiles
cannot generate body heat
internally, in the way that
mammals do, but they
can control their body
temperature by their
behavior. reptiles bask
in the sun to absorb
warmth, then hide in
the shade when they
become too hot.Coelophysis probably hunted
lizard-like reptiles and other
small animals of the time.BLue-TongueD Skink
The reptile’s tongue has several uses. Lizards and
snakes use it to detect their surroundings. The tongue
flicks out to pick up chemicals in the air and carries
them back to Jacobson’s organs, special sensory
organs in the roof of the mouth. When in
danger, the Australian blue-tongued
skink opens its mouth wide, thrusts
out its bright blue tongue,
hisses, and puffs up its
body to frighten away
a predator.BreeDing
most reptiles lay eggs, from
which the young hatch. Snake
and lizard eggs usually have
a leathery, flexible shell. The
eggs of crocodiles and tortoises
are hard and rigid, and the
temperature at which the eggs
are incubated determines the
sex of the hatchlings. The
loggerhead turtle, shown here,
digs a deep hole in the beach
sand and lays its eggs under the
cover of darkness. The eggs take
several weeks to hatch and are
at risk from foxes and monitor
lizards, which dig them up and
eat them. After hatching, the
young turtles have to avoid sea
birds and crabs as they scuttle
down to the sea.At dawn,
the lizard
sunbathes
with the
length of its
body facing
the sun to absorb
maximum heat.LArgeST AnD
SmALLeST repTiLeS
The saltwater crocodile is the largest
reptile, although some snakes, such
as the reticulated python, are longer,
growing to 33 ft (10 m) in length.
The largest lizard is the komodo
dragon, a type of monitor lizard. The
smallest of all reptiles are some kinds
of geckos, only about a half inch long
when fully grown.Turtles lay about 100
eggs in the sand.CoeLophySiS
The first reptiles
appeared on earth
more than 300
million years ago
and gradually
took over from amphibians as the largest
animals on land. Dinosaurs, such as the
Coelophysis shown here, were early reptiles that
evolved about 200–220 million years ago.
Coelophysis was about the size of an adult human.WALL geCko
Wall geckos have tiny sticky
pads on their toes, which
enable them to run up
smooth glass windows
and upside-down
across the ceiling.Some geckos are
smaller than the
human palm.The female loggerhead
turtle swims ashore
and crawls up
the beach
at night to
lay eggs.During the hot noon sun,
the lizard stays in the shade
to avoid overheating.Find out more
At dusk,
the lizard
basks with
its head
facing the
sun to keep
up its body
temperature.US_437_Reptiles_2.indd 437 22/01/16 4:47 pm