Class Notes 5: Energy Flow in Ecosystems

I. Energy Flow A. Ecologists trace the flow of energy through communities to discover nutritional relationships B. The sun is the ultimate source of energy that fuels life. C. Flow of energy Sun  Autotroph  Heterotroph  Decomposer

II. Autotrophs A. Autotrophs are the producers of their own nutrients Example: plants, algae B. Plants use the sun’s energy to make food in photosynthesis

III. Heterotrophs A. Heterotrophs are consumers incapable of producing their own food B. Types of heterotrophs include: 1. Herbivore: feed on plants only 2. Carnivore: feed on other animals 3. Omnivore: feed on plants and animals 4. Decomposer: break down and absorb nutrients from dead organisms (fungi, bacteria)

Which organism is the autotroph? Which is the herbivore? Which one is the omnivore?

IV. How ecologists depict energy flow: Types of models to use: A. Food chain: simplest, use arrows to indicate direction of energy transfer ex. grass  mouse  snake  hawk B. Food web:expresses all possible feeding relationships at each level of a community (more realistic, most organisms depend on more than one food source)

c. Pyramid of Energy 1.The base represents producers. 2. At each level, less energy is available % of energy is lost to the ecosystem as heat. 4. Only 10% of energy goes to the next level

Summary List the different ways organisms can obtain energy. What are some ways scientists show energy flow?