Fragmentation vs Regeneration
There are two types of reproduction methods existent among all the organisms living on this earth, namely, asexual reproduction and sexual reproduction. Asexual reproduction involves no exchange of genetic materials while sexual reproduction involves the exchange of generic material. Since there is no genetic material exchange taking place, the probability of occurring variations is very low in asexual reproduction. However, asexual reproduction is more advantageous when organisms are well-adapted to a constant environment with no significant changes. In animals, generally, asexual reproduction is limited to the invertebrate forms. Both fragmentation and regeneration come under asexual reproduction method. There are three main asexual reproduction methods; fission, budding and fragmentation.
What is Fragmentation?
Fragmentation is the process of breaking off a piece of organism followed by mitosis cell division. Meiosis is not involved in this process as it is a mode of asexual reproduction. The broken part can develop into an independent adult. Reproduction of sea anemones, star fishes, and flatworms are well-known examples for fragmentation.
Fragmentation process is limited to invertebrates, and it is absent in vertebrates. This is very common among cyanobacteria, molds, lichens, many plants and animals like sponges, flatworms and sea stars. The ability of fragmentation depends on the complexity of the organism. It may or may not be intentional and may occur naturally or by predators. Most of the time, after the splitting occurs, both fragments are capable of regenerating into complete individuals.
What is Regeneration?
Regeneration is a modified form of fragmentation. It is known as a process that makes genomes, cells organs, organisms, and ecosystems resilient after disturbances or damage. Every species living on earth can regenerate, but only a few species use it as an asexual reproduction method, thus producing new individuals by their body parts.
Planarian flatworms are highly adapted with regeneration capabilities because of their asexual reproduction method. Among the vertebrates, tailed amphibian (Salamanders and newts) and certain lizards (geckos) are highly adapted to regenerate their limbs, tails, jaws, eyes and certain internal organs. As they are more complex multicellular animals, they cannot use regeneration to reproduce or as an asexual reproduction method. Star fishes also have the same ability to regenerate their arm, but unlike tailed amphibians and lizards, lost arms of star fishes could regenerate a complete new organism.
There are two major steps in the regeneration process. Firstly adult cells de-differentiate into stem cells. Stem cells are similar to embryonic cells. These stem cells then develop and differentiate into new tissues thereby making new parts.
What is the difference between Fragmentation and Regeneration?
• Fragmentation is limited to invertebrate forms while regeneration is present in both vertebrates and invertebrates.
• Fragmentation is a method of reproduction (E.g. Star fish). Regeneration can be used as a reproduction method (E.g. Star fish) or it can be used to regenerate lost body parts (E.g. Lizards).
• In fragmentation, both parts produce new organisms while, in regeneration, when it is not for reproduction, the separated part cannot grow into a new organism.
• Regeneration is a modified form of fragmentation.
• Regeneration is more commonly seen in animals than in plants while fragmentation is more commonly seen in plants than in animals (E.g. Nonvascular plants).
• Fragmentation can be found only in certain organisms while various forms of regeneration can be found in almost all the animals living on the earth.