CHAPTER 4
ECOSYSTEMS and
COMMUNITIES
COMMUNITY INTERACTIONS

Competition


Predation


Compete for resources in order to survive
Predator and prey relationship
Symbiosis

Three kinds:
Mutualism
 Commensalism
 Parasitism

PREDATION

Predator—does the killing


Hawk
Prey—the organism that is being eaten

Mouse
MUTUALISM
“mutual” means “both benefits” or
“reciprocal relationship”
 Mutualism—both benefit, neither are
hurt
 Example:


Flowers and bees

Flowers and bees both benefit: Flowers are
pollinated by bees; bees receive nectar that
flowers produced. Neither are hurt in this
process
COMMENSALISM
One organism benefits
 The other is NOT harmed and does NOT
benefit
 Example:


Barnacles on a whale

Barnacles grow and receive nutrients while on
the whale. The whale is not harmed and does
not benefit from the barnacles.
PARASITISM
One organism benefits
 The other is harmed
 Example:


Tapeworms, fleas, ticks

Animal is harmed. The tapeworm, flea, or tick
benefits, receiving nutrients from animal’s body.