Regeneration
Pieces of a cut animal grow into whole animals.
A cut flatworm
Planaria is a simple flat animal. Suppose it is cut into three pieces.
What do you think each piece can do?
What this lesson covers
The idea
In regeneration, pieces of a cut organism grow into complete organisms through specialised cells that proliferate and change into various cell types in an organised sequence called development; it is not the same as reproduction.
A cut flatworm
Planaria is a simple flat animal. Suppose it is cut into three pieces.
What do you think each piece can do?
- Grow into a complete organism
- Stay as a piece and die
- Join the other pieces again
Cut and regrow
Press Next step.
Regeneration is not reproduction
Specialised cells make many new cells, and these change into the various kinds of cells and tissues in an organised order called development. Regeneration is not the same as reproduction, because most organisms would not normally depend on being cut up to reproduce.
In regeneration, pieces of a cut organism grow into complete organisms through specialised cells that proliferate and change into various cell types in an organised sequence called development. It is not the same as reproduction.
Notes
Regeneration: pieces grow into complete organisms through specialised cells that proliferate and change into various cell types in an organised sequence called development. It is not the same as reproduction.
Check yourself
Which simple animals can be cut into any number of pieces, each growing into a complete organism?
The organised sequence in which cells change into various cell types and tissues is called …
Why is regeneration not the same as reproduction?
- Amoeba and Plasmodium. These are single-celled organisms that divide by fission.
- Hydra and Planaria — correct. Yes!
- Spirogyra and Rhizopus. Spirogyra is a multicellular organism that breaks into fragments, and Rhizopus forms spores. The book names Hydra and Planaria for regeneration.
- fragmentation. Fragmentation is a multicellular organism breaking up into smaller pieces.
- budding. Budding is a bud growing as an outgrowth at one specific site.
- development — correct. Yes!
- Most organisms would not normally depend on being cut up to reproduce — correct. Yes!
- Regeneration makes no new cells. Regeneration is carried out by specialised cells that proliferate and make large numbers of cells.
- Regeneration happens only in plants. The book's examples of regeneration are the animals Hydra and Planaria.