While living in and on the host species, the animal parasite has evolved certain adaptations. Describe these adaptations with examples.
Parasites show the following types of adaptations:
(a) Morphological Adaptations: Many parasites are bigger in size than their free-living counterparts are. This helps in producing more eggs, necessary for survival. Endoparasites lose unnecessary sense organs to conserve resources. Endoparasites lose their gut or gut is reduced in size. They absorb nutrients through the skin. Special organs for attachment are present, e.g. suckers.
(b) Life Cycle Adaptations: An endoparasite needs some way to enter another host. Many parasites use a secondary host for this purpose. For example, plasmodium uses mosquitoes as secondary hosts so that they can easily infect another primary host. Some parasites lay their eggs in the lower portion of the alimentary canal of the host so that eggs or cysts can go out along with stool. Later on, the cysts get transmitted to another host through contaminated food and water, e.g. Entamoeba histolytica.
(c) Immunological Adaptations: Some parasites engulf antigens from the host. Some parasites disturb the immunological function of the host. These mechanisms help the parasite survive immunological response of the host.
(d) Biochemical Adaptations: Many endoparasites do not produce digestive enzymes. They rely on the host’s digestive enzymes and absorb the simple nutrients. Endoparasites do not carry out the synthetic reaction. This is possible because their energy need is very low, which is fulfilled from the host’s resources.