Reproductive System in Animals

Reproduction is one of the fundamental attributes of all living beings; a biological process that helps to produce new individuals of similar species. Moreover, with the help of this process, similar organisms can enhance their genetic variability and species continuation.

Usually, a species reproduces through the mating of female and male organisms. The reproductive organs of any organism are called gonads. These gonads create gametes. Reproduction in animals occurs when a male gamete and a female gamete merge to produce a unicellular organism known as a zygote. 

Types of Reproduction 

The process of reproduction in animals can be categorised in two types. Based on the number of participants, reproduction modes are-

• Sexual Reproduction

• Asexual Reproduction

1. Sexual Reproduction 

Both male and female parents are involved in sexual reproduction in animals. Sexual reproduction is the process of female and male gametes fusing to create new individuals.

Reproductive Organs in Animals

Reproductive organs of male include two testes, a penis, and sperm ducts. The testes produce sperms. The sperms are microscopic, and its structure has prominent three parts – a head, middle part and one tail.

Female gonads include two ovaries, oviducts, and one uterus. Ovaries create the eggs, and every month once the egg matures, it is transferred to the oviduct. The baby grows in the uterus.

Sexual Reproduction Process

Fertilisation

The first step of sexual reproduction in humans and animals is fertilisation. The male semen contains numerous sperms. By fusing one sperm with the egg, the fertilisation happens. During this process, the nuclei of both egg and sperm merge together to create a nucleus called zygote.

Two Types of Fertilisations are Found-

1. Internal Fertilisation

Internal fertilisation occurs inside the female body. Either sperm meet the egg through the reproductive tract of the female, or the males release the sperm and the females pick up and transfer the sperms in the reproductive tract.

Example- Human, other terrestrial animals like cow, dog, and some aquatic species, etc. Hence, reproduction in mammals occurs via external fertilisation.

There are Three Ways to Produce Offspring through Internal Fertilisation-

2.  External Fertilisation

External fertilisation happens outside of the female body, mostly during spawning. 

Example: Fish, frog, etc.

Development of Embryo

The unicellular zygote creates a ball of cells by several cell division, and this ball is called an embryo. Through implantation, this embryo gets attached to the uterus wall. Once the embryo starts developing organs and body parts, it is known as a foetus.

A child is a complete developed version of a foetus. 

2. Asexual Reproduction 

Contrarily, in the asexual reproduction process, a single organism can form new individuals irrespective of the gamete involvement and formation. Majorly, single –celled organisms take part in asexual reproduction. Furthermore, morphologically and genetically similar individuals are produced through this process.

Categories of Asexual Reproduction 

• Binary Fission

The parent cell divides into two identical cells containing one nucleus in each by mitosis.

Example: Euglena, amoeba, prokaryotes such as bacteria. 

• Fragmentation

Fragmentation is when an organism’s body breaks into different parts through any damage or otherwise, and each part develops into a single organism.

Example: Seastar.

• Budding

In budding, offspring grows on the outer part of a parent body and stays attached until maturation. When it matures, it separates and starts living as a single organism.

Example: Hydra.

• Regeneration

This is a modification of fragmentation where a completely new individual grows out of it.

Example: Echinoderm.

• Parthenogenesis

In this asexual reproduction in animals, the development of egg occurs without fertilisation.

Example: Ant, bees, etc.

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