Energy Roles Organisms may be producers,consumers, or decomposers These terms indicate how an organismobtains energy and how it interactswith the other living things in itscommunity.
Producers Means that they make theirown food Able to use a source ofenergy (sunlight) to turnsimple raw materials (such aswater and carbon dioxide)into food (like the sugarglucose). Producers are the source ofall the food in an ecosystem
Consumers Organisms that cannotmake their own fooddepend on producers forfood and energy. An organism that feedsdirectly or indirectly onproducers is called aconsumer.
Herbivores: eat onlyplants, such as rabbits Carnivores: eat only meat,such as wolves Omnivores: eat both plantsand animals, such as humans Scavengers: an animal thatfeeds on the bodies of deadanimals, such as jackals,hyenas, and vultures
Decomposers After living things die,organisms called decomposersuse the dead matter as food. Decomposers break down deadorganisms into simplersubstances. Molds, mushrooms, and manykinds of bacteria are examplesof decomposers
Essential to the ecosystem because they ridthe environment of the bodies of deadplants and animals They also return nutrients (compoundscontaining chemicals such as nitrogen,carbon, phosphorus, sulfur, and magnesium)to the environment, which are used by plantsto make food
Food Chains & Food Webs In general, food and energy in anecosystem flow from the producers to theconsumers in an ecosystem arerepresented by food chains and food webs. Food chains represent a series of events inwhich food and energy are transferredfrom one organism in an ecosystem toanother
Example: diatoms krill squid penguin killer whale A food chain gives you a glimpse of thefood and energy relationships in anecosystem, but it does not give you thewhole picture
– There are many organismsin an ecosystem and fewof them eat only one kindof food– There must be more thanone food chain in anecosystem A food web consists of manyoverlapping food chains
Feeding LevelsA feeding level is the location of anorganism along a food chainProducers form the first feeding levelHerbivores form the second feedinglevelCarnivores form the third feeding level
At each feeding level, organisms use theenergy they obtain to digest their food,reproduce, move, grow, and carry outother life activities This means there is less energy availableto each level as you progress up thefeeding levels These levels form an energy pyramid