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The Regeneration in planaria happens when they regenerate lost parts of the body. A planarian can be divided into pieces, and each piece can grow back into a full organism. The cells at the site of the wound multiply to form a blastema, which differentiates into new tissues and regenerates the severed planaria piece's missing pieces.
- The planarian may regenerate into a whole organism from tiny fragments estimated to be as little as 1/279th of the original organism over a few weeks.
- The extraordinary ability to regenerate is well-recognised among planarian flatworms.
- Regeneration is a kind of asexual reproduction.’
In the case a planarian is cut into many pieces, even more than halves, each piece will regenerate a new flatworm.
Also Check: Sexual and Asexual Reproduction
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Key Terms: Regeneration, Planaria, Flatworms, Neoblasts, Totipotent Cells
What is Regeneration?
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In regeneration, every fragment of an animal body that is broken up into smaller parts eventually forms a complete organism.
- Regeneration is an asexual reproduction method in which an organism can redevelop a body portion.
- Mitosis is the process used for regeneration. While one or more parents are concerned with the development of the organisms during reproduction, just one parent is concerned with the development of the offspring organisms during regeneration.
Regeneration examples include Hydra and Planaria. - Each body part can regenerate and contribute to the development of a whole Planaria (flatworms) when the body structure of a Planaria is broken up into several parts.
- An organism can regenerate by using the processes of growth. A ball of cells is created by dividing the reduced body cell portion.
- These many cells result in the development of tissues, the regeneration of organs, and the regeneration of all other Planaria.
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| Topic Related Concepts | ||
|---|---|---|
| Reproduction in Animals | Asexual Reproduction | Asexual Reproduction in Animals |
What Is Planarian?
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A planarian is a flatworm of the class Turbellaria, phylum Platyhelminthes, that is (mainly) free-living.
- Additionally, the term "planaria" refers to a specific genus, but the phrase "planarian" can refer to any member of the family Planariidae.
- The ocelli of planarian flatworms, which serve as their "eyes," have a cartoonish appearance.
Planarian Regeneration
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The ability of planarians to recover lost body parts that would be deadly to any other animal makes them particularly intriguing creatures.
- For instance, if you cut planaria in half, the two pieces will grow again as two different creatures.
- A planarian can be divided into several parts, and each piece will produce a new flatworm.
Regeneration in Planaria
Key to Regeneration
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Planarians are scientifically called Schmidtea Mediterranea, which have specialized stem cells called neoblasts.
Process of Regeneration
The process of regeneration includes:
- The regeneration process, in which lost tissues are replaced after an injury, depends on neoblasts. Neoblasts are also the only dividing cells in adult animals.
- This is similar to human totipotent stem cells, except these cells disappear after birth.
- Since they are the only cells that persist until adulthood and can divide in the adult animal, neoblasts in planarians are the key to regeneration.
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Things to Remember
- Regeneration is the process of developing back every fragment of an animal body that is broken up into smaller parts.
- Regeneration examples include Hydra and Planaria.
- A planarian is a flatworm of the class Turbellaria, phylum Platyhelminthes.
- Planarians are scientifically called Schmidtea Mediterranea.
- Planarians have specialized stem cells called neoblasts.
- Neoblasts are also the only dividing cells in adult animals and are similar to human pluripotent stem cells.
Sample Questions
Ques: Planaria reproduces in what way? Name the approach used. [Term 2, Set 2, 2017, CBSE Delhi] [1 mark]
Ans: The answer is that planaria reproduce by regeneration. When Planaria is divided into any number of pieces, each piece develops into a new organism in this sort of asexual reproduction.
Ques: What happens when any Planaria gets cut into two pieces? [CBSE Delhi, Term 2, Set 3, 2016] [1 mark]
Ans: When a Planaria gets cut into two pieces each piece regenerates into a new Planaria. This is due to the high totipotency in these animals.
Ques: Name any two simple organisms that can regenerate. [CBSE OD, Term 2, Set 3, 2015] [1 mark]
Ans: The two simple organisms in the animal kingdom that can regenerate are Planaria and Hydra.
Ques: (a) The asexual modes of reproduction include budding, fragmentation, and regeneration. Why?
(a) Describe the Planarian regeneration process using clear diagrams. [2019 CBSE OD, Set 3] [2 marks]
Ans: (a) Because only one parent is involved and there are no sex cells present, budding, fragmentation, and regeneration are all regarded as asexual modes of reproduction.
(b) Planaria's regeneration
Regeneration in Planaria
Ques: What process does Spirogyra use to reproduce when the conditions are right? Is this approach sexist or homosexual? [2017, CBSE Delhi, Term 2, Set 1] [2 marks]
Ans: Spirogyra reproduces by fragmentation under favourable conditions. This form of reproduction is asexual.
Ques: Describe one key distinction between asexual and sexual reproduction. Which species, one that reproduces asexually or one that reproduces sexually, is likely to have relatively better odds of surviving? Give justifications for your response. [CBSE 2018] [3 marks]
Ans: In contrast to sexual reproduction, which requires two parents and results in children that are distinct from their parents, asexual reproduction only involves one parent and results in clones and similar duplicates of the parents. Sexually reproduced children have a higher probability of surviving.
Sexual reproduction causes diversity because it produces kids whose DNA is a blend of that of both parents, improving the species' capacity for adaptation and likelihood of survival.
Ques: One of the most crucial aspects of living things is reproduction. Give the statement three justifications. [2017, CBSE OD, Term 2, Set 1] [3 marks]
Ans: Although energy-intensive, reproduction is not necessary for an individual's life. But for the following reasons, it is essential for all living things:
Reproduction contributes to the population growth of a group of people.
(ii) It reduces the likelihood that a species will go extinct by replacing the deceased individuals with new ones.
(iii) It causes species to varying, which promotes the evolution of those species.
Ques: What happens if (a) Planaria is accidentally sliced into a lot of pieces?
(b) A Bryophyllum leaf lands on the wet ground?
(c) Do Rhizopus sporangia burst during maturation? [2017, CBSE Delhi, Term 2, Set 1 ] [3 marks]
Ans: (a) Planaria will go through a process known as regeneration when it is cut into several pieces, causing each piece to develop into a new Planaria organism.
(b) Vegetative propagation occurs when a Bryophyllum leaf falls onto wet soil, causing the buds that form in the leaf's notches to grow into new plants.
(c) The Rhizopus sporangia mature and explode, dispersing the spores inside into the surrounding air. They are then transported to various locations with the aid of various agents, and once they touch down on an advantageous surface, they begin to grow and give rise to new organisms.
Ques: Describe the meaning of the word "regeneration" as it relates to organism reproduction. Describe briefly how multicellular organisms like Hydra carry out regeneration. [2016, CBSE OD, Term 2, Set 1] [3 marks]
Ans: The capacity of an organism to create new individuals or organisms from its body parts is known as regeneration.
If the body of a hydra is divided into pieces, each component of the body can develop into a whole hydra. In other words, when something is sliced into pieces, the cells of the damaged sections quickly divide to form a "ball of cells." The cells in the "ball of cells" travel to the appropriate locations inside the ball where they must build the different organs and body parts of the creatures.
Ques: (a) Draw a diagram to illustrate how Rhizopus produces spores.
(b) Differentiate between the processes of budding and fragmentation using an example.
(c) Why do some types of plants require vegetative propagation? [CBSE OD, 2020, Set 3] [5 marks]
Ans: The following can be shown:
a) Spore formation in Rhizopus
b) Regenerative cells are used for reproduction during budding in organisms like the Hydra. A Hydra bud forms as an outgrowth as a result of recurrent cell division at one particular location. When completely grown, these buds separate from the parent body and grow into new, independent individuals. They start as tiny individuals. This procedure is referred to as budding. Cell division leads to bud development. After that, the bud grows and gets a nucleus from the parent. This bud develops into maturity while still connected to the parent. Later, it separates from the parent cell and develops into a new individual that shares its parent's genetic makeup. These buds in some creatures can stay joined to the parent cell for a very long time, eventually forming a chain of buds.
Budding in Hydra
c) Simple reproduction techniques can be effective in multicellular animals with relatively simple body structures, such as Spirogyra. Upon maturation, the body merely disintegrates into smaller fragments. These bits and pieces develop into new people. Fragmentation is the term for this action. Multicellular organisms engage in a form of asexual reproduction known as fragmentation. Genetically, these people are similar to one another and their parents. Flatworms, sea worms, algae, jellyfish, starfish, fungi, and other Echinodermata frequently exhibit fragmentation.
Regeneration in Planaria
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