#22 Food Chains, Webs, and Trophic Levels

Warm-up Write one observation, one inference, and one way you think this relates to food chains/webs

*Food chain A food chain is the simplest path that energy takes through an ecosystem. Energy enters an ecosystem from the Sun The position of an organism within a food chain is called a trophic level. Arrows shows a transfer of energy amongst organisms. It also shows what organisms eat followed by what organisms consumes it.

*Food chain Trophic levels use some of the energy in the process of cellular respiration… C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + heat energy Each level loses 90% of its energy due to heat and stores the remaining 10%.

*1st Trophic level The first trophic level consists of producers (green plants) also known as autotrophs. Producers capture the Sun’s energy during photosynthesis, and converts it to form simple sugars.

*1st Trophic level Autotrophs (producers) use some of the sugars for energy and converts others to organic compounds (carbohydrates, proteins, and fats) that is needed for the structure and functions of the organism. Examples of producers include plants and phytoplankton.

*2nd Trophic level The second trophic level consists of primary consumers Primary consumers eat producers. Organisms that only eat plants are called herbivores. The herbivore uses some of the organic compounds for energy (10%) and much of the consumed energy is lost as heat (90%). Examples of primary consumers include grasshoppers, rabbits and zooplankton.

*3rd and 4th Trophic levels The third trophic level, or any higher trophic level, consists of consumers. 3rd level – are called secondary consumers and 4th level are called tertiary consumers. The consumer at the end of the food chain is also called the top carnivore

*3rd and 4th Trophic levels Consumers that eat other consumers are called carnivores; consumers that eat both producers and consumers are called omnivores. The carnivores or omnivores use some of the organic compounds for energy (10%) and much of the consumed energy is lost as heat (90%). Examples of consumers include humans, wolves, frogs, and minnows.

*More on Trophic levels Heterotrophs are organisms that cannot use the sun to make its own food. Heterotrophs are organisms that have to eat other organisms for energy. Which trophic level(s) are heterotrophs? heterotrophs that breaks down organic material and returns the nutrients to soil, water, and air making the nutrients available to other organisms are called a decomposer. Examples: fungi, mushrooms, earthworms, bacteria

Examples of food chains and trophic levels

*Food web A food web represents several interconnected food chains. It also shows the various paths that energy takes throughout an ecosystem.

Brainpop anyone? https://www.brainpop.com/science/ecologyandbehavior/foodchains/ https://www.youtube.com/watch?v=CReZd9OHEfs