The document discusses reproduction and development in different animal groups. It explains that birds incubate fertilized eggs externally through body heat until hatching, while reptile eggs do not require incubation due to protective shells. It also describes that fish eggs are fertilized externally in water and hatch into miniature adults, while amphibians undergo a metamorphosis from tadpoles to frogs. Finally, it notes that mammals either retain fertilized eggs internally and give birth to young, or are placentals, monotremes, or marsupials that develop in different ways.

2.  The eggs are fertilized inside the female’s
body by the male’s sperm. Shells are form
around the eggs.
 The eggs are then warmed and hatched
outside the mother’s body.
 Baby animals of birds, fowls and reptiles are
hatched from eggs.

3.  In the natural environment, the mother bird
sits on the eggs to keep them warm while the
embryo develops.
 Birds use their body heat to keep the eggs
warm. This is called incubation.
 To help keep warm and to protect them from
predators, birds build nest.

4.  Unlike birds, the eggs of reptiles do not need
incubation. They have leathery shells that
prevent moisture from escaping.
 Turtles lay their eggs on the beach.
 Alligators lay their eggs near rivers , ponds or
swamps.

5.  Fish spawn in the water since they live in it.
Their eggs are jellylike and have no shells. The
eggs are fertilized externally by the male’s
sperm. They are hatched as babies looking
like their parents.
 Amphibians are hatched as babies

6. 1. Eggs
2. Tadpole
3. Tadpole develop gills
4. Back legs appear
5. Front legs appear
6. Adult frog

7.  Some animals retain the fertilized eggs inside
the mother’s body until young one’s are
born.
- They look like their parents except that
they are smaller in size.
- These animals are fed with milk to
make them grow faster.
 Mammals are born as baby animals

8.  They can be divided into three groups
according to the way in which new
individuals develop from the fertilized eggs:
 Placentals
- mammals with placenta
 Monotremes
- egg-laying mammals
 Marsupials
- mammals with pouch