Parasitism is the biological interaction that originates between two organisms, in which one of them plays the role of host and the other of host. The living being who receives the parasite, gives you the power he needs to be able to survive. It should be noted that there are two types of parasites: those that live inside the host (endoparasites) and those that live outside (ectoparasites).
Parasitism represents the means through which a species extends its survival capacity using other species, so that they satisfy their basic and essential needs, which are not necessarily related to the nutritional part.
In the environment it is possible to find parasites of all taxonomic phyla and most of the living organisms have some species that parasitizes it. It is interesting to comment that all viruses are parasites, in the same way there are parasites that are bacteria and more microorganisms, animals and plants.
As already mentioned, within parasitism, the host is the parasite that benefits and the host, the one that is affected. The parasites that live within their host are endoparasites, they live most of their life within their host. Eg: intestinal worms, tapeworm tapeworm, etc. While those that inhabit the surface of another living being, it is known as ectoparasites. Eg lice, mites, ticks, fleas, etc.
Something that is very peculiar and common within parasites is that they end up losing genes and certain physical or metabolic functions when they become parasites. Many of them have stopped synthesizing their own molecules, since they can remove them from their host. An example of this are viruses, which are unable to reproduce without the molecular structure of their host.
Certainly over time, the hosts have continually developed in order to avoid being invaded by parasites. At the same time, the parasites have also been transforming in order to infect their host. This process that has just been mentioned is what is called coevolution, since the two species develop evenly.
