1. Organism Relationships
S7L4d
Categorize relationships between organisms that are competitive or mutually beneficial.

2. Each organism in an ecosystem interrelates with the other members
Each organism in an ecosystem interrelates with the other members. These relationships fall into one of three categories:
Symbiosis
Competition
Predation

3. Symbiotic Relationship
A long-term association between two members of a community in which one or both parties benefit
Three types of symbiotic relationships:
Commensalism
Mutualism
Parasitism

4. Mutualism Beneficial to both organisms Example:
Protozoa living in termite intestine
Protozoa break down wood the termite eats, while the termite provides food and shelter for the protozoa

5. Commensalism One member benefits and the other is unaffected
Barnacles that live on a whale
Barnacles don’t harm or feed on whale. They hitch a ride on the slow moving whale in order to catch plankton and other food in the water
Whale is neither benefited nor harmed

6. Parasitism
Benefits one organism (parasite), but harms the other (host)
Tapeworms in a human are parasites
Tapeworm benefits by getting its nutrition from the intestines of its human host
Host is harmed because there are not as many nutrients to absorb into its body.

7. A resource could be food, water, light, ground space or nesting space
Competitive Relationship
When two or more organisms seek the same limited resource, they compete with each other.
A resource could be food, water, light, ground space or nesting space
Competion can be intraspecific or interspecific.
Intraspecies competetion occurs between members of the same species
Interspecies competition occurs between members of different species

8. Predation Predator is an organism that feeds off of another organism
Prey is the organism it feeds on
Sea lions hunt down and kill herring
They harry the edges of the school of fish and eat until they have killed all the weak and sick animals
Sounds cruel, but without predation, competition and disease, there would be no natural limitations on population growth

9. May seem brutal that organisms feed off one another and awful that organisms perish from losing resources or getting disease, but the alternative is even more disastrous:
AN EVER-MORE-CROWDED WORLD IN WHICH EVERY POPULATION INCREASED UNTIL THERE WAS NO SPACE OR FOOD LEFT FOR ANYTHING OR ANYONE!
Ecological balances are important!