1. Symbiotic Relationships
Biology: Ecology Unit

2. Symbiosis
A close, long term relationship between two organisms of different species.

3. Types of Relationships
Predator-Prey
Mutualism
Parasitism
Commensalism

4. Predator - Prey
A predator is an organism that eats another organism.
The prey is the organism which the predator eats.

5. Examples Predator and Prey relationships
Animal - Animal
lion and zebra
bear and fish
fox and rabbit
Animal – Plant
Bear and berries
rabbit and lettuce
grasshopper and leaf.

6. Predator – Prey Environment
The prey is part of the predator's environment.
The predator dies if it does not get food, so it evolves whatever is necessary in order to eat the prey:
Speed
Stealth
Camouflage (to hide while approaching the prey)
Good sense of smell, sight, or hearing (to find the prey)
Immunity to the prey's poison, poison (to kill the prey)

7. Predator – Prey Environment
The predator is part of the prey's environment.
The prey dies if it is eaten by the predator, so it evolves whatever is necessary to avoid being eaten:
Speed
camouflage (to hide from the predator)
Good sense of smell, sight, or hearing (to detect the predator)
Thorns
Poison (to spray when approached or bitten)

8. Symbiotic Relationships
Three types of symbiotic relationships
Mutualism
Parasitism
Commensalism

9. Mutualism
Two different organisms benefit each other.
+ / + relationship
Examples:
Oxpecker (bird)/ zebra
Bird gets food by eating the parasites on the zebra
Zebra gets rid of the parasites on its body.
Bee / flower
Bees fly from flower to flower gathering nectar, which they make into food
Bees get pollen on their bodies and fly from flower to flower pollinating the plant

10. Parasitism
One organism, the parasite, lives off of another organism, the host, harming it and possibly causing death. The parasite lives on or in the body of the host. It will not kill it because it needs the host for survival.
+ / - relationship
Examples:
Tapeworms attach themselves to the insides of the intestines of animals such as cows, pigs, and humans. They get food by eating the host's partly digested food, depriving the host of nutrients.
Fleas harm their hosts, such as dogs, by biting their skin, sucking their blood, and causing them to itch. The fleas, in turn, get food and a warm home.
Parasitic plants can attach to other plants. Mistletoe attaches to trees, cutting off nutrients and causing it to die.

11. Commensalism Flowers / tree
One organism is benefitted and the other organism does not benefit or is harmed.
+ / 0 relationship
Examples:
Cattle / egret (bird)
Cattle walks around in pasture stirring up worms and insects for the egret to eat.
Cattle is not affected by sharing the pasture with the egret.
Flowers / tree
Some flowers grow up high on the tree to reach the sunlight.
Tree is not affected by these flowers growing up the tree.

12. Review A predator is an organism that eats another organism.
The prey is the organism which the predator eats.
Mutualism is the relationship when both organisms benefit.
Parasitism is the relationship when one organism is benefitted and the other is harmed.
Commensalism is the relationship where one organism benefits and the other organism is neither harmed or benefits.

13. Sources:
prey/co-evolution_predator.html
evolution/mutualistic/co-evolution_mutualistic.html
evolution/parasites/co-evolution_parasite.html
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