Asexual Reproduction

Asexual Reproduction in Animals

Reproduction of new organisms from a single parent, without the involvement of sex cells, is called asexual reproduction

Examples - Amoeba, Hydra

This type of reproduction involves only one parent. It takes place in microscopic animals like Amoeba and small animals like the hydra.

Budding in Hydra

  • Just like yeast, reproduction in hydra takes place through the process called Budding.
  • The Hydra possesses different bulges on itself called Buds.
  • These buds develop into individual Hydra. Each Hydra can possess a different number of buds.
 Budding in Hydra

Binary Fission in Amoeba

  • The Amoeba divides itself into two individuals and reproduction takes place in this way. It is called Binary Fission.
  • Amoeba consists of only one cell.
  • As it reproduces the nucleus of the Amoeba divides itself and forms two different nuclei.
  • Then the division of the body of the Amoeba takes place and each part receives one nucleus.
  • In this way, two Amoebas are produced from a single parent.
Binary Fission in Amoeba

Fragmentation and Regeneration

In some organisms, the parent organism divides itself into different fragments where each fragment then regenerates and develops into a new organism. This type of asexual reproduction takes place in Planaria and Starfish. Although, starfishes are capable of sexual reproduction as well but many times they also reproduce asexually with the process of fragmentation.

Fragmentation and Regeneration in Planaria

Parthenogenesis

In this type of asexual reproduction, female organisms are capable of producing eggs without fertilization. These eggs develop into a new organism. This type of reproduction can be seen in some fishes like sharks, some birds, reptiles like lizards and a few insects. However, it cannot be seen in mammals.

Difference between Sexual Reproduction & Asexual Reproduction

Important Terms

Asexual reproduction:  The mode of reproduction in which a single organism is able to produce one or more of its kind by itself is known as asexual reproduction; e.g., Amoeba, yeast, Hydra, etc., undergo asexual reproduction.

Binary fission: The type of reproduction in which an animal reproduces by dividing into two individuals is called binary fission; e.g., Amoeba reproduces by dividing itself into two.

Budding:  This kind of reproduction is seen in Hydra and yeast. It is the process of reproduction in which new individuals develop as outgrowths from a single parent. The outgrowths developed on the parent body are called buds and the process of reproduction is known as budding.

Embryo:  When cells produced by the division of the zygote begin to form groups that develop into different tissues and organs of the body is called the embryo.

External fertilization: The fusion of male and female gametes takes place outside the female body. This is called external fertilization. Most aquatic animals undergo this type of fertilization.

Fertilization:  The process of union of male gametes or sperms and female gametes or ova (egg) is called fertilization.

Foetus:  The stage of the development of the embryo in which the development and emergence of the various body parts like the hands, the feet and eyes, etc., can be identified is called the foetus.

Internal fertilization:  The fusion of male and female gametes or fertilization that takes place inside the female body is called internal fertilization. All insects, birds and mammals including human beings undergo this type of fertilization.

Metamorphosis:  A biological process in which larva drastically changes into an adult in an invertebrate or amphibian during their life cycle is known as metamorphosis.

Ova or Eggs: Female gametes produced by the ovary in females are called ova or eggs.

Oviparous animals: The animals which lay eggs and hatch them to produce their young ones are called oviparous animals; e.g., frogs, butterflies, hens, crows, etc.

Reproduction:  The process of producing the offspring of one’s own kind for continuity of life on the earth is known as reproduction.

Sexual reproduction: The type of reproduction that involves the fusion of male and female gametes is called sexual reproduction.

Sperms: Sperms are the male gametes produced by the testes in males.

Viviparous animals: The animals which give birth to their young ones are called viviparous animals; e.g., cow, buffalo, cat, dog, human beings, etc.

Zygote: The nucleus of the sperms and the egg fuse to form a single nucleus during the process of fertilization. The fertilized egg is called the zygote.