AMPHIBIA
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Introduction
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In earlier times there was a large variety of
amphibian life but today only a few groups
remain.
Of those still in existence, several live in water,
and even the terrestrial ones (those which live on
land) are partially dependent on water because
eggs are only laid in water and even the larvae
can develop only in water.
The amphibians are adapted to life both in water
and on land.
The only group of amphibians found in South
Africa is that which includes the clawed toad and
the various types of frog.
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Topics of Discussion
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THE FROG
HABITAT
BODY SHAPE
BODY COVERING
EXTERNAL STRUCTURE OF A FROG
BODY DIVISIONS
THE HEAD
THE TRUNK
THE LIMBS
THE CLOACA
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HABITAT
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Frogs live in water. They are
aquatic animals.
They prefer pools of stagnant
water, dams and slow-flowing
streams.
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BODY SHAPE
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The body is short because the frog
has no neck and tail. It has a hump
on its back.
The body is slightly flattened from
top to bottom.
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BODY COVERING
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The skin is soft and naked.
Large numbers of mucous glands
ensure that the skin is always
moist by secreting mucus.
Pigment cells also occur in the
skin. These enable the frog to
change colour in order to blend
into its sorroundings.
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EXTERNAL STRUCTURE
OF A TOAD
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BODY DIVISIONS
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The frog is divided into 2 divisions.
These are the head and the trunk
but there is no definite division
between these regions.
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THE HEAD
The head is flat and triangular in shape
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It is joined directly to the trunk
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It consists of the following parts:-(I)A
large mouth which opens widely to take
in food. Inside it there is
(a) Teeth only in the upper jaw. These are
not for chewing but for holding the prey.
(b) A large fleshy tongue which is sticky so
as to catch the prey. The tongue is
attached infront and free at the back, is
found on the floor of the mouth.
(ii) The two small nostrils are used for
smelling and breathing.
(iii) The two large bulging eyes enables it 9
to see moving objects. They are covered
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THE TRUNK
This forms the greater part of the body.
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It is flattened from top to bottom.
The following parts are found on the trunk:(i)
The limbs
The forelimbs are short and consist of an
upper arm and a forearm that ends in
four fingers.
The hind limbs are long and muscular.
(ii) The cloaca
The cloaca is situated at the rear end of the
trunk between the hind limbs.
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