Multiple Fission - Types of Asexual Reproduction
Multiple fission is a variation of fission where the parent divides mitotically into a number of smaller units that are the daughter individuals simultaneously. The nucleus in this case divides very fast, repeatedly. Subsequently the cytoplasm surrounding each daughter nucleus starts to form separate units leading to formation of small uninucleate, masses. These units become independent. This method of reproduction is as well known as schizogony and it occurs typically in Sporozoa and some Sarcodina. Schizogony is also termed as sporogony if it is associated with production of sporozoites after formation of zygote. A very good instance of multiple fission is seen in Plasmodium where sporozoites are introduced by the mosquito in the human host and where they enter the liver to go through several schizogonous cycles (pre-erythrocytic schizogony). The merozoites liberated from liver enter erythrocytes to go through another cycle of schizogony in which the schizont inside the human RBC undergoes multiple fission to generate merozoites. Can you visualise here that the parasite is exploiting the food resource to very rapidly multiply its numbers? That is one very significant benefits of asexual reproduction.
In addition to the dissimilar types of fissions described above, a modified type of fission in the form of budding takes place in suctorians. The adults bud off one or more smaller daughter cells. When buds are given off from the outer surface, it is termed as external budding. When budding takes place inside a chamber, buds arising from the wall of the chamber it is called internal budding. The buds, while released, possess ciliated bands and they swim around. But they soon attach to the substratum and become adults.