1. 21.3 Interactions among living things pg 722
Key concepts: How do an organism’s adaptations help it to survive?
What are the major ways in which organisms in an ecosystem interact?
What are the three types of symbiotic relationships?
Key terms: natural selection, adaptations, niche, competition, predation, predator, prey, symbiosis, mutualism, commensalism, parasitism, parasite, host

2. Adapting to the environment
Natural Selection – a process that selects individuals better suited to their environments to reproduce. It results in adaptations.
Adaptations – the behaviors and physical characteristics that allow organisms to live successfully in their environments.
Individuals who are poorly suited to the environment are less likely to survive and reproduce.

3. Niche
Every organism has a variety of adaptations that are suited to its specific living conditions.
The role of an organism in its habitat is its niche.
Includes type of food, how it gets food, which others use the same food
Also includes how and when the organism reproduces and the physical conditions it needs to survive

4. Competition
There are three major types of interactions among organisms: competition, predation, and symbiosis
Competition is the struggle between organisms to survive as they attempt to use the same limited resource (food, water, shelter)

5. Predation An interaction in which one organism kills another for food.
Predator – does the killing
Prey – gets killed
Effect of predation on population size: if there are many predators, a decrease in prey population will occur. When that happens, the predators will die from lack of food.

6. Predator adaptations
Speed, poisons, bigger eyes

7. Prey adaptations
Speed, defensive mechanisms (smelliness, ability to puff up or pretend to be bigger, pretending to be a different species, etc)
Mimicry
False coloring
Camouflage
Protective covering

8. Symbiosis
Symbiosis is a close relationship between two species that benefits at least one of the species
Three types occur: mutualism, commensalism, parasitism

9. Mutualism Both species benefit
E.g. saguaro cactus and long- eared bats
Bats get food and cactus gets pollen transfer

10. Commensalism
One species benefits and the other is not helped nor harmed
Red tailed hawk with saguaro cactus
Hawk gets a nest, cactus not affected

11. Parasitism One organism living on or inside another and harming it.
Organism that benefits is a parasite
Organism that is used is a host
Common parasites are ticks, fleas, leeches

12. Please complete
Page 729 section 3 assessment
1abc, 2abc, 3abc