The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:
The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:
Introduction
Reproduction is a way of producing offspring of the same species. Have you ever looked at the young ones of the animals and wondered how they were born? You might have already learned about plant reproduction, and now we will learn about reproduction in animals.
Give it a thought, what would happen if the animals, plants, or any organism stopped reproducing? They will be wiped off from the ecosystem. Since every individual plays an integral part in balancing the ecosystem of the earth, reproduction is necessary.
The reproduction in animals takes places in two ways, depending on the number of parents involved:
Like plants, animals have two different sets of reproductive species- Female and Male, and both have different reproductive organs called Gonads. The gonads form gametes. These gametes combine to create a zygote, a single cell that develops into a new animal.
However, certain animals like earthworms, snails, etc., have male and female reproductive organs in one organism and are called hermaphrodites.
Sexual reproduction in animals can be defined as when the gametes from both male and female fuse together to form a zygote, which then develops into a new individual. Now you must be wondering how the gametes can fuse? To understand that, let’s discuss the reproductive organs of both males and females.
Male Reproductive Organs
Male reproductive organ is made up of two sperm ducts, testes (a pair), and a penis. It is the testes that produce male gametes, called sperms. Testes can make millions of sperms. Sperms are microscopic in size (i.e., they cannot be seen with naked eyes), and each sperm has a tail (which helps in swimming), a middle part, and a head. In simpler words, sperms are a single cell that has all the necessary components of the cell.
Female Reproductive Organs
The reproductive organs in females consist of ovaries, uterus, and oviducts (also called fallopian tubes). The ovary produces ova (eggs) which are the female gametes. A mature egg is released into the oviduct every month by one of the ovaries. The baby develops in the uterus after the sperm successfully fertilizes it.
Reproduction begins when the sperm comes in contact with an ova or the egg. This merging of the sperm and egg is called fertilization. The nuclei of the egg and sperm together forms a single nucleus called the zygote.
Internal fertilization is the fertilization that takes place in the uterus of the female, i.e., inside the body of the female. Even though this fertilization method is commonly found in terrestrial animals, some aquatic animals also use this method to give birth to offspring.
There is another method of sexual fertilization that takes place outside the body of the female. Such fertilization occurs in water. In this method, the female lays thousands of eggs. These eggs are very delicate and have a thin jelly-like layer protecting the eggs. The sperm from male animal is deposited over the eggs. When the sperm and egg come in contact with each other, fertilization takes place. This is called external fertilization.
After the sperm and egg fertilize, a zygote is formed. The zygote makes balls of cells by dividing repeatedly. These cells then form into groups that further grow into different tissues and organs of the body. The structure formed is called an embryo, which attaches itself to the wall of the uterus to develop further. The embryo further develops hands, legs, and other body parts and is termed fetus.
As opposed to sexual reproduction, asexual reproduction is mostly seen in unicellular microbes and lower organisms. In asexual reproduction, a new individual is formed without the involvement of the gamete. There are different types of asexual reproductions:
Animals reproduce either sexually or asexually. Animals that can reproduce by themselves are called hermaphrodites.
Animals have two ways of reproduction: Sexual and Asexual.
Animals reproduce to give birth to young ones which will continue their species and save them from extinction.
Animals play an important part in the ecosystem. Their reproduction is necessary for the species to survive.
Unicellular animals like an amoeba, euglena, hydras, etc can reproduce asexually.
Starfish have eyes on each arm. When one arm is detached from the body, it grows back into a new starfish and the eye on the arm helps them see.
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In conclusion, reproduction in animals takes places in two ways: Sexual and Asexual. Sexual reproduction requires a male and female. In sexual reproduction, the sperm combines with the egg to form a zygote which further develops into a fetus and attaches itself to the wall of the uterus. While asexual reproduction requires a single parent which can divide itself into multiple cells to form new life.
