Asexual Reproduction in animals: Features, Types, Advantages & Disadvantages

Reproduction is the biological process of producing offspring from the parent organisms. Reproduction is essential for animals in order to make their survival possible. The living organisms basically reproduce to replicate themselves and reproduce similar organisms in order to compete with the other organisms in the environment. The biological process of reproduction involves sexual and asexual reproduction. The offspring produced are always genetically identical to the parents. The process of reproduction makes the existence of living organisms possible on earth. Reproduction is classified into two major types: sexual and asexual reproduction. In this article, we will have a look at asexual reproduction in animals which involves reproduction through a single organism without involving the fusion of gametes.

Keyterms: Reproduction, organisms, environment, sexual and asexual reproduction, living organisms, earth, gametes, fusion

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Asexual Reproduction in Animals

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Asexual reproduction in animals is a biological process of reproduction in living organisms in which an organism doesn’t need another individual organism to produce offspring. In asexual reproduction in animals, no merger of sex gametes takes place. The offspring is genetically identical to the parent organism because they belong to a single parent. This type of reproduction occurs only in invertebrates. A single-parent organism can produce a number of identical offspring at a time. The reproduced offspring are always well-versed with the environment that is stable for them because they are delivered in that particular environment. However, if the environment is unstable for the offspring, they will hardly adopt the environment and make survival possible. In asexual reproduction in animals, there is the presence of temporary gonads in the lower animals and permanent organs in the higher animals. Asexual reproduction occurs in prokaryotic microorganisms, many eukaryotic microorganisms, some unicellular organisms, and multi-cellular organisms. This type of reproduction does not include the union of gametes. 

Asexual Reproduction 

Features of Asexual Reproduction in animals

• In asexual reproduction in animals, no merger of sex gametes takes place. 
• The offspring is genetically identical to the parent organism because they belong to a single parent.
•  A single-parent organism can produce a number of identical offspring at a time.
• No change takes place in the number of chromosomes in asexual reproduction in animals.
• The genes of a single parent organism, whether a unicellular or multi-cellular organism, is carried by the offsprings.

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Types of Asexual Reproduction in animals

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The various types of asexual reproduction in animals are:

1. Fission: Fission is also called binary fission. It is a type of asexual reproduction in animals that usually occurs in prokaryotic microorganisms and some vertebrates (multi-cellular organisms). In fission, a parent organism splits into two separate organisms that are genetically identical. The eukaryotic microorganisms experience the process of fission by mitosis. The process of fission occurs mainly in planarians, sea anemones, asteroid echinoderms, and some coral polyps.

1. Simple Binary Fission: In this type of Binary fission, the organism splits into two parts. Each part carries a genetic material of its own.
2. Longitudinal Binary Fission: The gametes are not needed in this type of binary fission. A single-parent organism can reproduce offspring. 
3. Transverse Binary fission: The cytoplasm in the nucleus of an organism splits into two pairs of nuclei. This forms the two separate individuals.
4. Oblique Binary Fission: In this type, the organism is divided obliquely forming two unequal daughter cells.

Binary Fission of Amoeba

2. Budding: It is a type of reproduction that involves the outgrowth of a body part in a parent organism. The outgrown part detaches itself from the parent organism and results in the formation of daughter organisms. This type of reproduction also occurs in some multi-cellular organisms, for example, hydra. The bud grows on the body of a parent organism and is detached later from the body of a parent and forms individual offspring. 

1. External budding (Exodyogeny): External budding occurs in Hydra. A bud grows externally on the body of a parent organism. This bud detaches itself once it outgrows and a new hydra is formed. 
2. Internal budding (Endodyogeny): Usually occurs in parasites. In this type of budding, two daughter cells are produced inside a mother cell. The mother cell is consumed by the daughter cells at the time of separation. 
3. Strobilation: In this type of budding, transverse segmentation of the body takes place.

3. Fragmentation: Fragmentation is the process of reproducing offspring by breaking down the parent body into two individual organisms. This type of asexual reproduction in animals occurs mainly because of the damage to the parent body. If the body of a parent organism is large enough, each part grows into a separate offspring. For example, if the body of a parent starfish is cut into several pieces (with each arm having a piece of the central disc in it), each piece grows back into an individual starfish. 

4. Parthenogenesis: In this type of asexual reproduction, no fertilization of the eggs take place. The offspring can be diploid or haploid. It always depends upon the process involved and the species in which parthenogenesis occurs. This type of asexual reproduction in animals occurs mainly in invertebrates such as water fleas, rotifers, stick insects, ants, wasps, and bees. 

Parthenogenesis

5. Regeneration: In this form of asexual reproduction, the organisms can regenerate the lost or damaged part of their bodies. For example, if a lizard finds itself in a dangerous situation, it cuts off its tail but can regenerate the lost part of its body (tail). This type of asexual reproduction is found in plants also. 

1. Reparative regeneration: This means the regeneration or healing of the damaged part of a multicellular organism. 
2. Restorative regeneration: This means the regeneration of various parts of the body from a single fragment of a body. 

Regeneration

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Advantages of Asexual Reproduction in animals

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• Since offspring can be produced by a parent organism in a large number, the population increases rapidly.
• There is no need for another parent organism. Asexual reproduction in animals requires a single parent.
• Asexual reproduction in animals doesn’t include the fusion of gametes. No mating is required, thus involves less energy utilization. 
• The offspring are reproduced at a faster rate than sexual reproduction.

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Disadvantages of Asexual Reproduction in animals

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• There is a rapid growth in population in asexual reproduction. Hence, there is no control over the population of a particular species. 
• The offspring are biologically identical to a single-parent organism. No genetic variation takes place in this type of reproduction. 
• The conditions in the environment need to be suitable for the parent and offspring. 
• The species rely on the same environment for their survival making them compete with each other. 

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Things to Remember 

• Reproduction is essential for animals in order to make survival possible for them. 
• The biological process of reproduction involves sexual and asexual reproduction. 
• Asexual reproduction in animals is a biological process of reproduction in living organisms in which an organism doesn’t require another individual organism to produce offspring.
• In Asexual reproduction in animals, the offspring is genetically identical to the parent organism because they belong to a single parent. This type of reproduction occurs only in invertebrates.
• This type of reproduction does not include the union of gametes. No change takes place in the number of chromosomes. 
• Fission is a type of asexual reproduction in animals in which a parent organism splits into two separate organisms that are genetically identical. 
• Budding involves an outgrowth of a part of a body in a parent organism. The outgrown part detaches itself from the parent organism and results in the formation of daughter organisms. 
• Fragmentation is the process of reproducing offspring by breaking down the parent body into two individual organisms. 
• Parthenogenesis is the type of asexual reproduction in animals in which no fertilization of the eggs takes place. The offspring can be diploid or haploid. 

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