Differences Between Fragmentation and Regeneration, Practice Problems and FAQs

Lizards are one of the most commonly seen reptiles in Indian homes. Many of us are very scared of these home lizards, also known as the house Gecko. Do you know what the fear of lizards is called? The fear towards reptiles is called herpetophobia.

But have you ever thought about this from the perspective of a lizard? What runs in their minds when they see us? You must have noticed that upon a sudden encounter with a human, the lizard would simply shed its tail and run off. Why do you think it does so? This is an escaping technique called caudal autotomy which is used to confuse the perceived predator to be able to run away. But does the lizard die after shedding its tail? Not at all, instead, the tail will grow back again. This process is called regeneration.

Fig: Caudal autotomy in lizard

Is this the same process, adapted by the plants, when we cut the plant parts and make them grow? The answer is no, because this process is called fragmentation, in which new plants are formed from parts of their parents. There are many animals which can also generate new organisms through regeneration. Even though both the processes seem to be similar, there are many differences between them. Let’s discuss more in this article.

Table of contents:

• Fragmentation
• Regeneration
• Difference between fragmentation and regeneration
• Practice Problems
• FAQs

Fragmentation

The type of asexual or vegetative reproduction or cloning, where the splitting of the body of an organism into two or more pieces occurs to give rise to new individuals from the split parts is called fragmentation. Each part after splitting is called a fragment and each fragment develops into a new organism. During fragmentation the organisms develop specific organs or zones to be easily shed. Each organism from the fragment will be a clone of the parent and become free living individuals.

GIF: Fragmentation in starfish

The major organisms which exhibit the fragmentation are as follows:

• Specific plants
• Fungi
• Filamentous cyanobacteria
• Lichens
• Sponges
• Sea anemones
• Flatworms
• Annelid worms
• Sea stars

Fragmentation in plants

Fragmentation is a common method of vegetative reproduction in plants. When a shoot that is rooted gets detached from the main plant, it will start to grow as an individual plant. This is how fragmentation happens in plants. Fragmentation is more common in non vascular plants than in vascular plants.

Specialised structures like offsets, stolons, runners, rhizomes, and bulbils also help in the process of fragmentation. Adventitious rooted plantlets are found in some plants which can grow into new individual plants when detached from the parent plant. Eg: Bryophyllum.

In non-vascular plants like mosses the fragments are carried by means of wind, animals or water. When these fragments reach a suitable environment, they grow into a new plant.

Fig: Mosses (Funaria)

Algae such as Spirogyra also break into fragments, each of which grow into an individual organism.

Fig: Fragmentation in algae

Artificial fragmentation methods are also used by people to propagate plants. The major methods of artificial fragmentation are as follows:

• Cutting
• Layering
• Grafting

Fragmentation in animals

The animals split into two or more parts while undergoing fragmentation and each part develops into a new organism with all the organs present in the parent. This process of asexual reproduction is seen in animals like sea anemones, sea stars, sponges, flatworms, and annelids.

Fig: Fragmentation in sponges

Types of fragmentation in animals

According to the plane of splitting in animals, there are two types of fragmentation and they are as follows:

• Architomy - splitting of an organism at specific parts to produce two fragments, each of which can regenerate the missing tissues and organs. The developments of tissues that are to be lost does not precede the splitting process. Furrows may develop at the zone of splitting. Thus, the organism splits into multiple parts each of which grow into a new individual, e.g, Hydra.

Fig: Architomy in Hydra

• Paratomy - splitting at a particular point perpendicular to the anterior-posterior axis in the posterior section and the regeneration of anterior structures preceded this process.

Regeneration

The complete or partial regrowth, renewal and restoration of an organ or tissue of an organism is called regeneration. From a small body fragment a whole body can be regenerated. Most of the living organisms have the ability to regenerate. Molecular processes like gene regulation and cellular processes like cell proliferation, cell differentiation, and morphogenesis are taking part in the process of regeneration.

Types of regeneration

The two types of regeneration on the basis of the percentage of body parts which regrows are as follows:

• Complete regeneration - regrowth of entire lost limb or organ, eg: certain worms and starfishes.
• Incomplete regeneration - regrowth of partial limb or organ, eg: fishes and amphibians.

Regeneration in plants

In plants the regeneration process can happen naturally by the growth of a new leaf or shoot from the stem.

Regeneration in animals

Due to the adaptive regenerative capacities of Hydra and Planaria, they have served as model organisms for the process of regeneration. Any wound in their body makes the cells activate and restore the organs into their original state.

Types of regeneration

The two types of regeneration in animals are as follows:

• Reparative regeneration
• Restorative regeneration

Reparative regeneration

When the broken or lost body part get repaired or replaced, then it is called reparative regeneration or epimorphosis. It is also known as partial regeneration. The total regeneration of the tail of a lizard which shed after escaping from the enemy is an example for this type of regeneration. Other examples are the regeneration of a lost arm of a starfish and the regeneration of a partially damaged liver.

Restorative regeneration

When the whole body is regenerated from the small body fragment, then the regeneration is called restorative regeneration. It is also known as true regeneration. The animals which show restorative regeneration are Hydra, Planaria, Flatworms. Starfish occasionally show restorative regeneration.

Difference between fragmentation and regeneration

The major difference between fragmentation and regeneration are as follows:

Practice Problems

1. Which of the following is a wrong statement about the fragmentation?

1. Each fragment develops into a new organism.
2. Fragmentation is a common vegetative reproduction in plants.
3. Fragmentation is more common in vascular plants.
4. Specialised structures like stolons, rhizomes, and bulbils also help in the process of fragmentation.

Solution: The type of asexual or vegetative reproduction or cloning, where the splitting of the body of an organism into two or more pieces is called fragmentation. Each part after splitting is called fragments and each fragment develops into a new organism. Fragmentation is a common vegetative reproduction in plants. Fragmentation is more common in non vascular plants than in vascular plants. Specialised structures like stolons, rhizomes, and bulbils also help in the process of fragmentation. Adventitious rooted plantlets are found in some plants which can grow into new individual plants when detached from the parent plant. Hence the correct option is c.

2. Which of the following are the artificial fragmentation methods used to propagate plants?

1. Cutting
2. Layering
3. Grafting
4. All the above

Solution: Artificial fragmentation methods are also used by people to propagate plants. The major methods of artificial fragmentation are cutting, layering and grafting. In cutting, the vegetative part of the plant is cut and buried in the soil. Layering is the method of producing roots from the branch of a plant which is covered inside the soil. In grafting the two fragments of two desirable plants are combined together to produce a new superior plant. Hence the correct option is d.

3. Which of the following is the true regeneration?

1. Complete regeneration
2. Incomplete regeneration
3. Reparative regeneration
4. Restorative regeneration

Solution: When the whole body is regenerated from the small body fragment, then the regeneration is called restorative regeneration. It is also known as true regeneration. The animals which show restorative regeneration are Hydra, Planaria, Flatworms. Starfish occasionally show restorative regeneration. Hence the correct option is d.

4. Which of the following shows both fragmentation and regeneration?

1. Lizard
2. Hydra
3. Planaria

1. 1 and 2
2. 2 and 3
3. 1 and 3
4. All the above

Solution: The animals split into two or more parts while undergoing fragmentation and each part develops into a new organism with all the organs present in the parent. This process of asexual reproduction is seen in animals like sea anemones, sea stars, sponges, flatworms (Planaria), and annelids. Architomy is the splitting of an organism into multiple parts each of which grow into a new individual, e.g., Hydra, Planaria. When the whole body is regenerated from the small body fragment, then the regeneration is called restorative regeneration. It is also known as true regeneration. The animals which show restorative regeneration include Hydra, and Planaria. Due to the adaptive regenerative capacities of Hydra and Planaria, they have served as model organisms for the process of regeneration. Any wound in their body makes the cells activate and restore the organs into their original state. Hence the correct option is b.

FAQs

1. What are the disadvantages of fragmentation?

Answer: The process of fragmentation results in the formation of clones. As a result it does not make any genetic diversity. Hence the offsprings are more vulnerable to the changing environments, diseases and parasites. Another disadvantage is that this process is always not desirable or possible.

2. What is venom regeneration?

Answer: Some organisms like scorpions have the ability to regenerate their venoms and it is called the venom regeneration. The content of the venom which is regenerated is different from the original venom. Before the active proteins are replenished, the venom volume gets replaced.

3. What is autotomy?

Answer: The process of shedding one or more appendages of an animal by themselves is called autotomy or self amputation. They do this as a part of self defence mechanism from predators. This can distract the predator. Some have the ability to regenerate their lost appendages.

4. What kind of animals are called polyphyodont?

Answer: The animals whose teeth are continuously replaced in their lifetime are called polyphyodonts. Examples are toothed fishes, crocodiles, geckos. Most vertebrates except mammals also show this.