Asexual Reproduction in Animals

 

Asexual Reproduction in Animals

Besides sexual reproduction, the other major type of reproduction seen in the animal kingdom is asexual reproduction. This type of reproduction is mostly observed in lower organisms and unicellular microbes.

It is the process in which a new individual is formed by the involvement of a single parent without the involvement of the gamete formation. The individuals produced are genetically and morphologically similar. The cells divide by mitotic division and no fertilization takes place. The division occurs very rapidly.

Types Of Asexual Reproduction

Asexual Reproduction is of the following types:

Binary Fission

It is seen in amoeba and euglena. The parent cell undergoes mitosis and increases in size. The nucleus also divides. Two identical daughter cells are obtained, each containing a nucleus. Prokaryotes like bacteria majorly reproduce by binary fission.

Budding

In this, the offspring grows out of the body of the parent. It remains attached to the parent until it matures. After maturation, it detaches itself from the parent and lives as an individual organism. This form of reproduction is most common in Hydras.

Fragmentation

In some organisms like Planarians, when the body of an organism breaks into several pieces each piece grows into an individual offspring. This is known as fragmentation. It can occur through accidental damage by predators or otherwise, or as a natural form of reproduction. In a few animals such as sea stars, a broken arm grows into a complete organism.

Regeneration

It is a modified form of fragmentation and occurs mostly in Echinoderms. When a part of an organism, like an arm, detaches from the parent body, it grows into a completely new individual. This is known as regeneration.

Parthenogenesis

This is a form of asexual reproduction where the egg develops without fertilization. This process occurs in bees, wasps, ants, aphids, rotifers, etc. Ants, wasps, and bees produce haploid males. Parthenogenesis has been observed in a few vertebrates such as hammerhead sharks, Komodo dragons, and blacktop sharks when the females were isolated from the males.