Reproduction in Animals
Reproduction is the biological process by which an individual
organism gives birth to its young one. Animals can reproduce by two modes ?
(i) Sexual reproduction,
(ii) Asexual Reproduction.
The mode of reproduction in which an individual can reproduce
without involvement of another individual of that species is called asexual
Sexual reproduction is the type of reproduction in which two
individual, called parents, are needed to reproduce the young ones.
Human male reproductive system consists of a pair of testes
(singular testis), two sperm ducts and a penis.
Human female reproductive system consists of a pair of ovaries,
oviducts (fallopian tubes) and the uterus.
The testes produce male gametes called sperms and the ovary
produces female gametes called ova.
In sexual reproduction, male gamete fuses with female gamete. The
fusion of ovum and sperm is called fertilization and the fertilized egg is
called a zygote.
The zygote divides repeatedly to give rise to an embryo which
gets embedded in the wall of the uterus for further development.
The stage of the embryo in which all the body parts are
identifiable is called foetus.
Fertilization that takes place inside the female body is called internal
fertilization. This type of fertilization is observed in human beings and other
animals such as hens, cows and dogs.
Fertilization that takes place outside the female body is called
external fertilization. This type of fertilization is observed in animals like
frogs, fish, starfish, etc.
Animals which give birth to their young ones are called
viviparous animals. Human beings, cows and dogs are some examples or the
Animals which lay eggs are called oviparous animals. For example,
hen, frog, lizard and butterfly etc.
Some animals physically develop after birth or hatching,
involving a conspicuous and relatively abrupt change in their body structure
through cell growth and differentiation. This transformation of the larva into
adult through drastic changes is called metamorphosis.
Binary fission and budding are some of the methods of asexual
reproduction, Hydra reproduces by budding and amoeba reproduces by binary