1. Relationships

2. Community Interactions
Competition - Occurs when more than one organism uses a resource at the same time including food, water, space, and light. If resources are scarce then competition runs high. If resources are plentiful then competition is lower.
Predation - The act of one organism consuming another organism for food.
Predator - the organism that pursues.
Prey - the organism that is pursued.

3. Symbiotic Relationships
Symbiosis - The close relationship that exists when two or more species live together.
The lichen fungi (kingdom Fungi) cultivate partners that manufacture food by photosynthesis. Sometimes the partners are algae (kingdom Protista), other times cyanobacteria (kingdom Monera), formerly called blue- green algae. Some enterprising fungi exploit both at once.
Three types of symbiosis: mutualism, commensalism and parasitism.

4. Mutualism
The relationship between two or more organisms that live closely together and benefit from each other.

5. Commensalism Commensalism
A relationship in which one organism benefits and the other organism is neither helped nor harmed.
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6. Parasitism
A type of relationship in which one organism benefits at the expense of another organism.
Internal parasites - bacteria, tapeworm, roundworm, heartworm
External parasites - ticks and fleas