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Unit 18: Biology Part 1 Page 30 of 60
animals. Instead, it is based on Turtles have excellent vision,
environmental factors. The allowing them to see well at night
temperature surrounding an egg and see in color. Turtles living on
shortly after it is laid determines if land generally have eyes that point
a male or female crocodile will down, allowing them to see what is
hatch. right in front of them. Sea turtles
Crocodiles are well-suited for a hot, have eyes higher up. This allows
aquatic environment. By holding them to hide them from predators,
their mouths open, a process completely submerged except for
known as gaping, crocodiles cool their eyes and nostrils. Sea turtles
off. Additionally, crocodiles can can also cry salty tears, allowing
breathe underwater. A set of them to rid themselves of some of
internal nostrils in the crocodile’s the salt in the water they are in.
throat, are closed off by the tongue Turtles do not have teeth. Instead
when the crocodile goes they have ridges in their jaw. In
underwater, allowing it to breathe. carnivorous turtles, these ridges
There are about 500 species of are sharp enough to rip apart prey.
turtles, many of which are highly Herbivorous turtles, or turtles
endangered. Turtles are that eat plants, have ridges
characterized by having a large, designed for grinding and tearing
protective shell made of bone or through tough plants.
cartilage, which comes from their Like most reptiles, turtles lay
ribs. Although many turtles live in leathery eggs. As we saw with
or near water, they lay their eggs crocodiles, some species of turtles
on land. Turtles also must come have environmentally-determined
up to the surface to breathe gender in offspring. Remember
through their lungs. that this meant that the
temperature early in the embryo’s
fertilization determined if the
offspring would be male or female.
Reptiles help humans in many
ways. Snakes and lizards prey on
many pests, from insects to
rodents. Having these reptiles
The shell of this Eastern Box Turtle around keeps the number of pests
comes from its ribs.
down, reducing disease. Snake
venom has also been used in the
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