If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Competition, predation, and mutualism

NGSS.MS:
MS‑LS2‑2
,
MS‑LS2.A.4
Predatory interactions may reduce the number of organisms or eliminate whole populations of organisms. Mutually beneficial interactions, in contrast, may become so interdependent that each organism requires the other for survival. Although the species involved in competitive, predatory, and mutually beneficial interactions vary across ecosystems, the patterns of interactions of organisms with their environments, both living and nonliving, are shared. Created by Sal Khan.

Want to join the conversation?

  • male robot hal style avatar for user KEVIN
    How do scientists agree upon what to call these processes? It seems that scientists in Africa might have a slightly different perception of mutualism, for instance, and subsequently, a different name for it, than a scientist from say, Sweden.
    (7 votes)
    Default Khan Academy avatar avatar for user
    • starky ultimate style avatar for user ++§ Αλεκσανδαρ
      Can you provide an example? As far as I can tell, the discoverer usually proposes a name, and the community either accepts the term or proposes something more appropriate. All communication (at least nowadays) is going via scientific papers. Most terms used have their origins in Latin language. For an example, mutualism is derived from Latin word mutuus, which means reciprocal, done in exchange. This fits into the description of what mutualism is.
      I think this term has the same meaning and should be used in the same context both in African and Swedish textbooks. If you know an example where it isn't so, I'd be interested to look at it.
      (12 votes)
  • aqualine ultimate style avatar for user Jasmine
    What would happen to a species if one animal that was in a mutualistic relationship with another animal became extinct? What would happen to the other animal?
    (5 votes)
    Default Khan Academy avatar avatar for user
  • aqualine ultimate style avatar for user ShawnVF
    What is the reason why humans are on top of the food chain?
    (3 votes)
    Default Khan Academy avatar avatar for user
  • aqualine ultimate style avatar for user Kate
    How do the birds eat ticks and lice off of ox or cows,not get sick or affected? Do those birds have a special digestion process? Do they eat rocks like some birds do and the rocks kill them?
    (3 votes)
    Default Khan Academy avatar avatar for user
    • aqualine ultimate style avatar for user cyuutekat
      Well, it's mainly because starlings eat bugs! Since starlings are capable of digesting (hopefully) a wide range of insects, they're able to eat right off an ox's back. Now, if your question is "Why don't starlings get sick because of the bacteria and stuff on the ox's skin-fur thing?" then it's probably because of natural selection. Bird 1 has immunity to bacteria on ox, Bird 2 does not, Bird 1 survives and produces offspring, Bird 2 dies. Hope this answers your question!
      (3 votes)
  • leafers ultimate style avatar for user S F
    Do humans not have mutualism because we're horrible for the environment?
    (2 votes)
    Default Khan Academy avatar avatar for user
  • mr pink red style avatar for user simone modica
    If the birds eat the parasites off the bull how does the bird not get effected?
    (2 votes)
    Default Khan Academy avatar avatar for user

Video transcript

- [Instructor] All across ecosystems, we know that organisms interact in specific ways and scientists use special words to describe these types of interaction, competition, predation and mutualism. So let's first talk about competition which we have already talked about in other videos. In this picture here, do you see competition? Pause this video and think about that. Well, one limited resource that these animals need to survive is water. There's only a limited amount in this watering hole over here and so you could imagine there is competition not just amongst the members of a population let's say between the zebra but also between members of different species, between different populations in a community. The zebras are not just competing for water with each other but also with these antelope or with these buffalo over here. There might also be competition for food. It doesn't seem like there's a lot of grass to eat for all of these animals that like to graze on grass. So now let's move on to predation. Predation is when one organism eats another organism usually to its own benefit. Do you see any predation happening here? Well, we don't see any of these animals chasing and killing each other. There might be other animals like lions offscreen that might hunt and kill and eat these animals right over here but we know that these animals do eat grass and as I said, it's not just about hunting and killing and eating from one animal to another. It could be one organism to another. So the eating of the grass by these animals could actually be considered a form of predation especially if it kills the grass. A more obvious form of predation is this brown bear here that has gotten the salmon out of this river. It is clearly hunting and killing the salmon for its benefit and it is likely that each of these bears are in competition with other bears for this limited resource. So last but not least, let's think a little bit about mutualism. Mutualism happens when two organisms benefit from interacting with each other. Right over here, we have these starlings that actually hang out on this buffalo and pick lice and ticks off the buffalo's fur. This is mutualism because both parties benefit. The starlings are able to get food and the buffalo no longer have these parasites, these things that are living off of the buffalo sucking its blood out of its body and also probably not itching as much. Now, based on how I just described it, there's not just mutualism here. There's also predation because these birds are actually hunting and killing the lice and the ticks on the buffalo's body. Now, related to being a predator is another word known as being a parasite and that's what the lice and the ticks are doing where they're sucking the blood of the buffalo but they're not considered predators. They're more parasites because they don't kill the buffalo. They're just taking some resources away from it. So I'll leave you there. I encourage you when you look at nature, when you go to a park next time, when you go watch a documentary, I encourage you to think about how competition, predation and mutualism is happening in an ecosystem that you are seeing or that you're a part of.