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Chapter – 9 Reproduction in Animals
Reproduction is a process in which theorganisms produce theyoung ones oftheir own kind. There are twomodes by whichanimals reproduce. Theseare: (i) Sexual reproduction, and (ii)Asexual reproduction
Sexual Reproduction
Reproduction resulting fromthe fusion ofmale and female gametes is called sexual reproduction.
The reproductive organs in the female include ovaries, oviducts and uterus. Thereproductive organs inmale include testes, sperm ducts andpenis.
The ovary produces female gametes called ova andthe testes produce male gametes called sperms.
The fusion ofovum and sperm is called fertilization. Thefertilized egg iscalled a zygote.
Fertilization that takes place inside the female body is called internal fertilization. This 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. Thisis observed infrogs, fish, starfish, etc.
The zygote divides repeatedly to giverise to anembryo.
The embryo gets embedded inthe wall ofthe uterus forfurther development.
The stage ofthe embryo inwhich all thebody parts areidentifiable is called foetus. Animals such as human beings, cows and dogs which give birth to young ones are called viviparous animals.
Oviparous Animals: Animals that lay eggs are called oviparous animals, e.g., frogs, lizards, butterflies, etc. The transformation of the larva into adult through drastic changes iscalled metamorphosis.
Asexual Reproduction
The typeof reproduction in which onlya single parent is involved is called asexual reproduction. In hydra, new individuals develop from buds. Thismethod of asexual reproduction is called budding. Amoeba reproduces bydividing itself intotwo. This typeof asexual reproduction is called binary fission.
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