Symbiosis and parasitism

In short: Symbiosis describes close biological relationships between different species, which can range from mutual benefit to the exploitation of one partner. Parasitism is a form of symbiosis in which only one side benefits.

In more detail: A basic distinction is made between mutualism, commensalism, and parasitism, based on the relationship between benefit and harm.

In detail

• Mutualism: Both partners benefit, such as bees and flowering plants during pollination.
• Commensalism: One partner benefits, the other is neither harmed nor helped, as with some bird species on large animals.
• Parasitism: The parasite uses the host for its own benefit while harming it, such as tapeworms in the intestine.
• Ecto- and endoparasites: Ectoparasites live outside the host, like ticks, while endoparasites live inside, like intestinal worms.
• Coevolution: Host and parasite often develop together over long periods, leading to increasingly fine-tuned adaptations.
• Lichens as an example: Lichens consist of a close symbiosis between fungi and algae or cyanobacteria.
• Importance for ecosystems: Symbiotic relationships are often crucial for the stability of entire ecosystems (insekten-und-bestaeuber, nahrungskette-und-oekosystem).