Topic outline

    • Animal Life – Reproduction in Animals

      You must have seen sometime, bird feeding their babies or dog playing with their puppies or monkey hugging its baby. Do you wonder at the similarity between animals and their babies? We observe that animal and their babies have same characteristic and features. Both animal and their young ones have same pattern of hair, skin, tail etc.


      Why do animals have babies similar to them?

      All living thing reproduce to replace their old and dying forms. If they do not reproduce their form will disappear from the earth. Example: If cat does not reproduce, they will not be seen in future after some time. So, reproduction is vital process for every animal to continue its race.

      Reproduction is a process by which living organism produce another one of their own kind.


      How do animals reproduce?

      Two main ways of reproduction

           1.   By laying eggs

           2.   By giving birth to young ones

      Animal That Lay Eggs

      Some animals reproduce by laying eggs. These include insects, fish, frogs, snakes, lizards, snails, birds and crocodiles.


      Bird builds nest to lay eggs. Birds nurture their eggs to keep them at the proper temperature, before these eggs hatch into young ones.

      All eggs are protected by hard covering made of calcium carbonate called the shell. Shell is porous that allows the transfer of gases through the shell. Within the shell are the albumen (white) and the yolk (yellow). Albumen contains protein that is necessary for development of growing bird and Yolk is the source of food, contains the fat. The young bird will only develop at the proper temperature, this happens only when bird sits on them for several days.

      When the baby bird hatches from the egg, they do not have feathers. So, the bird feeds their young ones till their feather develops.


      Most of the insects such as butterflies, grasshoppers, cockroaches and houseflies lay eggs. The young ones when come out of eggs look very different from their parent. During their growth, they keep shedding their outer layer or covering of their body and gradually develop into adult. This process of shedding off outer covering of the body i.e. skin by the baby insect during their growth is called Moulting.

      Small baby cockroach or grasshopper that hatches from egg is called nymph. They do resemble their parent but lack wings. After shedding their skin several times, they turn into adult.

      Butterfly and housefly eggs when hatches, small worms come out called larva. The larva of butterfly is called caterpillar and larva of housefly is called maggot.


      Life Cycle of Butterfly

      Butterfly lay eggs on leaf and tiny worm like structure hatch from the egg called larva (caterpillar). Caterpillar eats leaves all the time and becomes plump and sluggish. When it cannot eat more, it covers itself from the thread that comes out of the caterpillar’s body. This stage is called pupa. The caterpillar undergoes many changes inside the cocoon. This change occurring in the form, structure, or function of organism in the process of its growth or development is called metamorphosis. After few weeks later, a beautiful butterfly comes out of cocoon.

      Life Cycle of Frog

      Frogs lay eggs in water or wet place. Eggs hatches into small tadpoles. These tadpoles look more like a fish rather a frog. Tadpole has no legs but has a long tail and breathes through gills in water. They feed on pond weeds and gradually turns into froglets and then into frog. An adult frog breathes through lungs.


      Lizards, turtle and snakes also lay eggs but do not give any parental care. Most of their laid eggs are eaten by other animals. Among reptiles only crocodiles and their relatives tend both eggs and babies. Crocodiles make nest in the ground and lay eggs there. They carry their babies to the water body after the egg hatches and took care of them for some time.


      Animals that give birth to young ones

      Some animal give birth to young ones. Such animal are called mammals. This includes animals such as dogs, cats, monkeys, tigers, cows, elephants, horses and humans. The baby develops inside the mother’s body. After their birth they feed on mother’s milk till they learn to feed by their own.

      Whales and dolphins lives in water but they give birth to young ones. Bat though a bird gives birth to young ones.

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