1. 22.3 Interactions Among Living Things

2. There are three major types of interactions among organisms: competition, predation, and symbiosis.

3. Competition is the struggle between organisms to survive in a habitat with limited resources.

4. Predation is an interaction in which one organism kills and eats another organism.
Prey
Predator
                                              

5. Predators have adaptations that help them catch and kill their prey.

6. Prey organisms have adaptations that help them avoid being caught and eaten.

7. Predation can have a major effect on the size of a population.

8. Symbiosis is a close relationship between two species that benefits at least one of the species.
                                              

9. Mutualism is a relationship in which both species benefit.
African Buffalo with oxpeckers
Lichen on a rock

10. Red tailed hawk in a saguaro cactus
Commensalism is a relationship in which one species benefits and the other species is neither helped nor harmed.
Remoras on a turtle
Red tailed hawk in a saguaro cactus

11. Parasitism involves one organism living on or inside another organism and harming it. The organism that benefits is called a parasite, and the organism it lives on or in is called a host.
Beef tapeworm
Flea in dog’s fur