Advantages of Metagenesis in Cnidaria
In this you have studied that a huge number of Cnidarian colonies are polymorphic and exhibit alternation of generations. This changes of generation or metagenesis confers tremendous advantages for the specific species.
a) Proximate (immediate) Benefits
i) Metagenesis gives alternative method of reproduction, asexual and sexual, in case either one fails to work.
ii) Sessile (attached to the substratum) forms such as Obelia produce free moving medusae as part of metagenesis. This allows wider distribution of species, which in turn improves the chances of exploring and finding better shelter, food and environment.
iii) Metagenetic animals escape adverse climatic conditions through changing from one body form to the other body form.
b) Ultimate Benefits
Continuous asexual reproduction causes genetic homogeneity. To avoid this, alternate sexual forms permit cross fertilization mixing of genetic material and variation which is good for species survival and evolution. In addition to Cnidarians, polymorphism is clearly seen between certain, orders of the Class Insecta of Phylum Arthropods.