Physique
The shell of a turtle consists of carapace and plastron. The inside of the shell is bone tissue that is united
with the ribs of the turtle. The bones of the shell are covered with horny scutes. In most semiaquatic turtles the
shell is fairly flat compared to the high domed tortoises shells.
The shell is not as resistant as it looks. Between the horny scutes and the bones there is a sensitive skin layer with
blood vessels and nerves. Therefore touches and temperature changes can be sensed.
Damage or abrasion of the shell may result in bacteria or other
pathogens gaining access to the skin layer and cause shell-rot.
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The limbs of turtles are adapted to the medium through or on which they travel. Semiaquatic turtles have strong hind limbs
and webs between the toes. The fore limbs are rather lean.
C.reevesii have almost no webs on the hind limbs and are therefore known to be poor swimmers. Mostly they walk around on
the ground, and they frequently leave the water to bask in the sun.
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Senses
Semiaquatic turtles have a strongly developed sense of smell. They are able to smell even under water.
Everything that looks interesting and might be edible will be nosed. The eyes are important for orientation
and to sense approaching enemies. Movements are noticed from distances of 30 to 50 meters. Turtles can see
colours and are able to orientate three-dimensional.
The sense of hearing is secondary, only low frequencies can be noticed.
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Sexual dimorphism
The size and shape of the tail is often an unique distinctive feature in semiaquatic turtles. The male has a pronounces
bulge at the base of its tail because of the drawn-in penis. The vent opening is beyond the edge of the carapace, and the tail
is noticebly longer than that of a female.
In many turtle species the female grows bigger than the male.
The sex of C.reevesii can be securely specified at an age of four. Sexual maturity can be expected
at an age of 6-8 years. Male turtles tend to become completely black at an certain age, but this is not
a valid criterion to determine the sex.
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