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Energy Flow in an Ecosystem Energy Flow in an Ecosystem • Autotrophs: organisms that manufacture their own nutrients using stored energy or energy from the sun – Examples? • Heterotrophs: cannot make their own food, they feed on autotrophs or other heterotrophs – Examples? Energy Flow in an Ecosystem • The sun is the ultimate source of energy for all organisms • Producers change light energy into energy they can use to grow. – Plants and other photosynthetic organisms • Consumers eat other organisms instead of producing their own food • Decomposers are organisms that break down the remains of organisms – Fungi, bacteria, some insects Types of Consumers • Herbivores: feed on plants – Rabbits, grasshoppers, squirrels, etc • Carnivores: feed on other animals – Lions, snakes, wolves, etc • Scavengers: feed on dead animals – Vultures, crows, etc • Decomposers: break down and absorb nutrients from dead organisms – Fungi, bacteria, some insects Energy Flow in an Ecosystem • Energy flows through an ecosystem as one organism eats another. The way in which energy flows can determine how many species can live in an ecosystem. • Each step in the transfer of energy through an ecosystem is called a trophic level – In an ecosystem, energy flows from the sun to producers to consumers to decomposers Trophic Levels in an Ecosystem Energy Flow in an Ecosystem • Food Chains – In an ecosystem, energy flows from one trophic level to the next, forming a food chain – Simple way to show flow of energy from one trophic level to the next – Arrows point in the direction of energy flow Energy Flow in an Ecosystem • Food Webs – Energy does not follow a simple pattern! – Many organisms eat more than one kind of food – A group of interconnected food chains form a food web Energy Flow in an Ecosystem • Energy is stored at each level of a food web and moves throughout trophic levels as organisms feed on each other. But not all of it is used; some of it dissipates as heat back into the environment and does not move on to the next trophic level…. Energy Flow in an Ecosystem • Rule of 10 – Also called “The 10% Rule” – Only TEN (10) PERCENT of the energy available in a trophic level will move on to the next! – The other NINETY (90) percent is changed into heat energy! Energy Flow in an Ecosystem • Energy Pyramid – Triangular diagram that shows an ecosystem’s loss of energy as it moves through a food chain – Each layer represents one trophic level • Producers are always at the base. They have the MOST energy! • Consumers make up higher levels