[Biology Class Notes] on Parasitism Pdf for Exam

The relationship between two species where one organism which is called the parasite lives on or within the body of the other organism which is called the host, this relationship is known as parasitism. Parasites cause some kind of harm to the body of the host. In order to increase the fitness of its own, a parasite tries to gain food or shelter in the host’s body and reduces its fitness.

Types of Parasites

On the basis of where parasites live, they have been classified into three categories-

1. Ectoparasites- The parasites that live upon the surface of the body of the host are known as ectoparasites. Examples of ectoparasites are fleas, ticks, etc.

2. Endoparasites- The parasites that live inside the body of the host are known as endoparasites. Examples of endoparasites are- roundworms, protozoa in blood, etc.

3. Meso Parasites- The parasites that enter the host body through an opening and embed themselves are known as meso parasites. An example of mesa-parasites is a copepod.

Parasites on the Basis of the Life Cycle

Parasites can be distinguished on the basis of their life cycles into two categories-

1. Obligate Parasite- The parasites which require the bodies of their host in order to survive are known as obligate parasites. 

2. Facultative Parasite- The parasites which do not require the bodies of their hosts in order to complete their life cycle are known as facultative parasites.

Parasites on the Basis of their Strategies

Parasites are classified on the basis of their strategies into three categories-

1. Directly Transmitted Parasites- The parasites that reach the body of their hosts on their own are known as directly transmitted parasites. Examples are fleas and mites.

2. Trophically Transmitted Parasites- The parasites which are entered in the body of hosts when they eat them are known as trophically transmitted parasites. Examples are trematodes and roundworms.

3. Vector Transmitted Parasites- The parasites which are dependent on the intermediate host which will take them to their definitive host are known as vector transmitted parasites. Example- Protozoan that causes sleeping sickness that is transported by insect bites.

Other Types of Parasites:

1. Brood Parasitism- Parasitism in which young parasites are raised by the hosts is known as brood parasitism. Example- Cuckoo.

2. Klepto Parasitism- The parasitism in which the food of the host is stolen by the parasite is known as kleptoparasitism. Example Skuas stealing food

3. Sexual Parasitism- The type of parasitism in which the males are dependent on the females for survival is known as sexual parasitism. Example- anglerfish

Advantages of Having Parasites Around

Since parasites spread harm to the body of their hosts, it is believed that they are dangerous and should be eradicated. Yet, on the other hand, parasites are very useful for the ecosystem in the following ways-

• Parasites control dominant species.

• They allow competition and diversity.

• Parasites help in the transferring of genetic material between the species.

Conclusion

Parasites are present in every biological Kingdom such as animals, plants, fungi, protozoa, bacteria, viruses, etc. Some of the parasites are roundworms, mosquitos, all viruses, and malaria-causing protozoans. Students can achieve good marks on this topic by practicing from .