Interspecific Relationships - Negative Interactions > Parasitism

Parasitism is an interaction between two species in which one (known as parasite) obtains its food in ready‑made form from the other living organism (said to be host).

• Parasitism is a relationship where the parasite benefits and the host is harmed (food, shelter).
• Many parasites are host-specific and co-evolve with their hosts.
• Parasites have special adaptations like loss of sense organs, hooks/suckers, and high reproductive capacity.
• Parasitism reduces the survival, growth, and reproduction of the host and may make it more vulnerable to predators.
• Parasites often have complex life cycles involving one or more intermediate hosts (e.g., liver fluke, malaria parasite).
• Two main types: Ectoparasites (live on host surface, e.g., lice, ticks) and Endoparasites (live inside body, e.g., liver, RBC).
• Brood parasitism: Birds like cuckoos lay eggs in another bird’s nest, and the host incubates them.