Parasitism is a type of biological relationship where one organism benefits while the other is harmed.
The organism that benefits is called the parasite, and the one that is harmed is called the host.
How it works
- The parasite lives on or inside the host
- It takes nutrients, shelter, or resources from the host
- The host is usually weakened, injured, or slowly harmed, but not always killed immediately
Examples
- Ticks on dogs → ticks feed on blood, dogs lose nutrients
- Tapeworms in humans → absorb food nutrients from the intestines
- Plasmodium (malaria parasite) in humans → damages red blood cells
Key idea
Parasitism is different from:
- Mutualism → both organisms benefit
- Commensalism → one benefits, the other is unaffected
In parasitism, the relationship is one-sided benefit with harm to the host.
If you want, I can also explain how parasites survive inside the host without getting killed by the immune system—it’s surprisingly clever biology.
