DEFINITION: Parasitism is the relationship between two organism or animals or plants of different species, in which the organism of one species interact with another for its own survival. Sometimes It may be harmful for the host organism which provides nutrients or shelter to the parasitic organism.
*PARASITE: The organism which depends on another organism (Host) and take nutrition from the host`s body for survivals and use the host body as shelter, is known as parasite. Examples: a. Mosquito is a parasite and it sucks blood from the human body (host) and use it as their food. b. Roundworm is a parasite and take shelter in the intestine of human and collect nutrients from the host body and reproduce in intestine. There are many other examples of parasites.
Mosquito sucking blood of human host.
*HOST: Host is another organism of this biological interaction (parasitism) which provides nutrients to the parasites and acts as their shelter. Which is very beneficial for the parasitic organism but vary harmful for its own self and sometimes causes death to it. Examples: Human is host of the mosquito and roundworm as discussed above. But there is also some other example of host such as – A dog that has fleas. Louse, is a ectoparasite of human host.
Louse on human hair
Interaction between host and parasite: In parasitism the parasite completely or partially depend on the host. Some times they use the host body as their shelter and some times sucks nutrients from the host body which is necessary for their survival but dangerous for the host itself. according to the dependency of the parasites on the host body they are classified differently. Mainly they are two types- a. Ectoparasite and b. Endoparasite.
Ectoparasite: A parasite which live outside of the host body and depend on the host for consuming food for their survival. Example- louse is an ectoparasite present on the out side of the human host, the take shelter in hairs.
Endoparasite: The parasites which are present inside the host body and survive and reproduce inside the host body is known as endoparasite. Example- Ascaris or roundworm is an endoparasite and live in human intestine.