Energy Flow Pyramids and Trophic Levels

Plant material eaten by caterpillar Does all the energy this caterpillar eats get passed to the bird who eats him? Plant material eaten by caterpillar 100 kilocalories (kcal) 35 kcal Cellular respiration 50 kcal Feces 15 kcal Growth

TROPHIC LEVELS Determined by the organism’s source of energy Organisms are identified by their trophic level according to their name. Autotrophs Heterotrophs Decomposers Decomposers are a specific type of heterotroph.

1. AUTOTROPHS: Capture energy from the sun (photosynthetic) or inorganic molecules = chemicals (chemosynthetic) and converts it into usable energy. Also known as PRODUCERS produces food (make energy storing molecules), Eg. Plants, algae and some kinds of bacteria

2. HETEROTROPHS- Obtains the energy to build their molecules by consuming plants or other organisms Also known as CONSUMERS Includes not only primary, secondary, tertiary (etc.) consumers, but also include: decomposers and detritivores

3. DECOMPOSERS A specific type of heterotroph Can be one of two types: -Scavenger/Detritivore: Eats dead organisms (carcasses) or detritus (dead organic matter) Eg. Bear, Dog, Vulture, Crab, Worm, Bacteria -Saprotroph: Digests matter, extracellularly (outside the cell) by spitting enzymes out and then absorbing the digested material. Eg. Fungi such as mushrooms

Pyramid Models: graphs which illustrate the trophic levels in a community.

Energy Pyramid Model Organisms convert food (glucose) into energy. This energy is given off as heat which is lost to space. Energy is a one way path. It is not a cycle.

Energy Pyramid Model An energy pyramid is a diagram that compares energy used by producers, primary consumers, and other trophic levels. As a rule each trophic level receives only 10% from the trophic level below. In other words each trophic level loses 90% heat to the atmosphere.

Energy Pyramid Model Producers: 123,000 KJ Primary Consumers: Tertiary Consumers: 123 KJ Secondary Consumers: 1,230 KJ Primary Consumers: 12,300 KJ Producers: 123,000 KJ

Biomass Pyramid Biomass is the mass of organisms minus water. Biomass refers to the amount of carbon and other trace elements in an organism’s body contains.

Numbers Pyramid Illustration of the number of organisms at each level

It depends on what they are eating. How can more people be supported on Earth when there is a limited supply of resources? It depends on what they are eating.