parasitism definition biology

What is Parasitism in Biology?

Parasitism is a type of symbiotic relationship between two species, in which one species (the parasite) relies on the other species (the host) for food and shelter. The parasite will usually live off the host, taking resources from the host and sometimes damaging it in the process.

Types of Parasitism

There are several different types of parasites:

  • Ectoparasites: These are external parasites that live on the surface of the host, such as fleas and ticks.
  • Endoparasites: These are internal parasites that live inside the body of the host, such as tapeworms and worms.
  • Parasitoids: These are parasitic insects that lay their eggs inside other insects and consume them as they hatch.

Effects of Parasitism

Parasitism can have a variety of effects on the host organism, ranging from mild to life-threatening. These effects can include:

  • Nutrient loss: Nutritional resources are taken from the host, which can lead to malnutrition.
  • Organ damage: Parasites can damage organs and tissues in the host, leading to life-threatening diseases.
  • Behavioral changes: Parasites can alter the behavior of their host, causing it to display unusual activities.

Parasitism in Nature

Parasitism is an important part of natural ecosystems, affecting many species of plants and animals. A large number of species rely on parasitism as part of their life cycle, and the complex interrelations between parasites and their hosts can help regulate population dynamics.


Parasitism is a common and important biological interaction, and understanding the different types of parasites, their effects on the host, and their role in the environment is an important part of biology. In conclusion, the parasitism definition biology is a type of symbiotic relationship in which one organism (the parasite) lives off of another (the host), usually at the host’s expense.

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