What are the major types of interactions among organisms?
Sometimes the major interactions are divided into five categories: predation, competition, parasitism, mutualism, and commensalism.
While there are other interactions, these five categories cover most of the interspecies interactions.
Predation is when an organism kills and eats another. This does not just mean carnivores; even cows eating grass count as predators!
Competition is when two organisms are trying to get the same resource, such as food, water, shelter, mates, territory, etc. This is an extremely common interaction.
Parasitism is when one organism lives off another, but usually does not kill it. Examples include ticks, tapeworms, malaria, and more.
Mutualism is when two organisms have a mutually beneficial relationship. The clownfish and anemone are a common example. The clownfish gets protection while the anemone gets cleaned, so both organisms benefit.
Finally, commensalism is a relationship where one organism benefits and the other is unaffected. For example, barnacles (small crustaceans) often attach to whales. This allows them to have greater access to food as the whale moves, but does not really help or hurt the whale.