Organisms can interact in different ways.

Chapter 2

Section 2

Predator and Prey

Predator: an animal that eats another animal Prey: an animal that is eaten by a predator

– In a food chain, an animal can be both a predator and a prey

Competition

The struggle between individuals or different populations for a limited resource

Occurs between members of different species or

Occurs within the same species– Plants may compete with each other for light,

space, and nutrients

Cooperation

An interaction in which organisms work in a way that benefits them all

Example: Ants, bees, and termites live in colonies. Members of the colonies have different responsibilities like gathering food or defending the colony

The survival of one species might depend on another species.

Symbiosis: relationship between individuals of two different species who live together in a close relationship– May affect the partners in different ways

Both species benefit

Mutualism: an interaction between two species that benefits both– Example: termites live off of wood – they have

tiny singled celled protozoans living in their guts that help them digest the wood. The protozoans get a safe place to live, and the termites can take advantage of a plentiful food source

One Species Benefits

Commensalism: a relationship between two species in which one species benefits while the other is not affected– Example: Some fish protect themselves by

swimming among the stinging tentacles of a moon jellyfish. The fish benefit because the tentacles keep them safe and the jellyfish is not helped or hurt by the presence of the fish.

One species is harmed

Parasitism: a relationship between two species in which one species benefits while the species it depends on, its host, is harmed.– Example: Parasites are often tiny organisms that

feed off, and weaken, their hosts. Tapeworms and ringworms live inside their hosts.

Symbiotic Relationships

Mutualismbenefits both

Commensalism benefits one, other unaffected

Parasitism benefits one, harms other