Page 16 - Science class 4

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The air sac contains air which One Step AheadOne Step Ahead
the developing chick breathes
The egg hatches and baby bird come
in while it is inside the egg.
out of it. This is called hatching.
Did You Know?
The habit of sitting on their eggs by some animals to keep them warm is
called incubation.

When baby bird gets fully developed, the egg hatches and the baby bird

or chick comes out of it. The chicks do not have feathers and their eyes are

closed. The parent bird feeds and looks after them till they start moving.

Fish

Fishes lay eggs in water. They lay thousands of eggs
at a time. The mass of eggs produced is called

spawn. Fish eggs do not have shells. They are

covered with a type of jelly that protects them from
water. Out of thousands of eggs, only a few hundred

grow into baby fish. Many eggs and baby fish are

eaten up by big fish. The baby fish is called fry . A fish laying eggs

Reptiles

Reptiles like crocodiles , snakes , lizards and turtles
lay eggs on the ground. Their eggs are protected by

shells which are like thick leather . As a result, these
eggs do not break when laid on the ground. The
A Baby snake coming
out from an egg eggs are warmed by the heat of the Sun. The baby
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comes out breaking the egg shell using a One Step AheadOne Step Ahead
special egg tooth. Most reptiles do not care for
A frog can live on land
their eggs or babies. Many eggs and young
but its babies cannot.
ones are eaten up by other animals.
Frogs
Frogs also lay hundreds of eggs at a time. They lay eggs in the water in a safe
places. Their eggs are covered with jelly. The life-cycle of a frog has four stages.
The eggs hatch into tadpoles. Tadpoles looks like tiny little fishes. Tadpoles

have tails that help them to swim in water and eat water plants. After a few

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