1. Chapter 18 Interactions of Living Things Mr. Perez

2. Important Vocabulary Ecology Abiotic factor Biotic factor Population Community Ecosystem Biosphere Population density Limiting factor Symbiosis Niche Habitat Producer Consumer Decomposer Food chain Food Web

3. Ecology The study of interactions among organisms and their environment. Ecologists organize the environmental factors that influence organisms into two groups Abiotic factors- non-living parts of the environment Biotic factors- living or once-living organisms in the environment

4. Abiotic factors WaterWater All organisms need water to surviveAll organisms need water to survive Organism bodies are 50%-95% waterOrganism bodies are 50%-95% water Important in cytoplasm in cellsImportant in cytoplasm in cells Respiration, photosynthesis, digestion and other important life processes can’t happen without waterRespiration, photosynthesis, digestion and other important life processes can’t happen without water More than 95% of the Earth’s surface water is found in the oceanMore than 95% of the Earth’s surface water is found in the ocean

5. Abiotic factors Light and temperature Sunlight is important for plants and other photosynthetic organisms Temperature can determine which plants/animals can live there Air Composed of gases including nitrogen, oxygen and carbon dioxide Needed for respiration Soil Soil type is determined by the amounts of sand, silt and clay Different kinds contain different nutrients, minerals and moisture

6. Biotic factors Levels of organization: Organism Population Community Ecosystem Biome Biosphere

7. Characteristics of Populations Population size can be difficult to measure because individuals are too widespread or move around too much Instead, we estimate the population size (sampling) The size of a population is always changing Births Deaths Migration Immigration

8. Characteristics of Populations Population density- the number of individuals in a population that occupy a definite area Ex: If 100 mice live in an area of one square kilometer, the population density is 100 mice per square kilometer Population spacing is how the organisms are arranged in a given area Evenly- consistent distance between them Randomly- each organism’s location is independent of the locations of other organisms Clumped- resources such as food or living space are clumped

9. Limiting factors Any biotic or abiotic factor that limits the number of individuals in a population Competitors Weather Predators Fires Available habitat Disease/parasites

10. Carrying Capacity The largest number of individuals of a species that an environment can support and maintain for a long period of time If a population gets bigger than the carrying capacity, some individuals are left without adequate resources and will either die or be forced to move elsewhere Biotic potential The maximum rate at which a population increases when plenty of food and water are available, the weather is ideal, and no disease or enemies exist

11. Symbiosis and Other interactions Symbiosis: any close interaction between two or more different species Mutualism: two different species of organisms cooperate and both benefit (+ +) Lichens = fungus + algae Commensalism: one organism benefits without affecting the other organism (+ 0) Flatworm that lives in a horseshoe crab’s gills Parasitism: two different species in which one species benefits and the other species is harmed (+ -) Mistletoe grows into a tree’s roots and takes away nutrients

12. Symbiosis and Other interactions Predation is a way to regulate population size Act of hunting, killing and feeding on another organism Habitats and niches Habitat: place where an organism lives Niche: role, or job, of an organism in the ecosystem

13. Classwork Questions On a separate sheet of paper answer the following questions. You do not have to write these questions, but the answers should be in complete sentences. 1.Compare and contrast abiotic factors and biotic factors. Give five examples of each that are in your ecosystem. 2.Describe a population and a community. 3.Explain how biotic factors change in an ecosystem that has flooded.

14. Classwork Questions Write down the following questions. Answer them as you watch the videos. 1.Name three pairs of animals that work together in the video. 2.Describe what each animal offers its partner (if anything). http://www.youtube.com/watch?v=uxVMeLWzB _o

15. Energy Flow Through Ecosystems Organisms interact with members of their own species and other species Food chains or food webs consist of: Producers- organisms that take in and use energy from the Sun or some other source to produce food Consumers- organisms that take in energy when they feed on producers or other consumers Decomposers- take in energy as they break down the remains of organisms

16. Food chains Simple way of showing how energy, in the form of food, passes from one organism to another Arrows indicate the direction of energy transfer Usually only have three or four links because energy decreases/is lost as it is transferred Lost as heat*

17. Food Webs Series of overlapping food chains that exist an ecosystem Provides more complete model of energy transfer in an ecosystem More accurate, because they show more organisms

18. Ecological Pyramids Most of the energy in the biosphere comes from the Sun Producers take in and transform only a small part of the energy that reaches the Earth’s surface Primary consumers eat producers Secondary consumers eat other consumers Tertiary consumers eat only secondary consumers (usually at the top of the food chain/web)

19. Ecological Pyramids Organisms can be classified as: Autotrophs- can produce their own food Heterotrophs- cannot produce their own food Carnivore- must eat other organisms Herbivore- must eat producers (plants) Omnivore- can eat both plants and other organisms

20. Energy Pyramids Only about 10% of the energy at each level of the pyramid is available to the next level

21. Classwork questions On a separate sheet of paper answer the following questions. You do not have to write the question, but the answers should be complete sentences. 1.Draw and label a food web that includes you and what you’ve eaten today (or yesterday). 2.Compare and contrast producers, consumers and decomposers. 3.Use your knowledge of food chains and the energy pyramid to explain why fewer lions than gazelles live on the African plains.

22. Videos http://www.vtaide.com/png/symbiosis.htm

23. Resources Florida Science Grade 8 Glencoe Science & McGraw Hill Publishing Google Images