Energy Flow in an Ecosystem

Biomass The total mass of living plants, animals, fungi and bacteria in a given area

Organisms have special roles, or niches, in the ecosystem in which they live. Within its niche, every organism interacts with that ecosystem in two ways: The organism obtains food energy from the ecosystem The organism contributes energy to the ecosystem

Food Webs Herbivores – eats plants Carnivores – eats animals Omnivores – eats plant and animals Insectivore – eats insects Top predator Top predator Consumers: all animals + fungi + some bacteria Producers: all plants + some bacteria

What happens when organisms die? When organisms die, they become detrius DETRIUS is all the dead plants, dead animals, and animal waste Detrius – contains organic (carbon containing) and inorganic compounds

Detrivores Detrivores – organisms like snails, beetles, and earthworms that EAT detrius. This helps decomposition because it increases the surface area of detrius

Decomposers Decomposers – organisms like Bacteria and Fungi break detrius into smaller molecules (nutrients) that can be absorbed by other organisms Nutrients are recycled back into ecosystem

Biodegradation Biodegradation – if something is biodegradable then it can be decomposed by Bacteria and Fungi Example: many plastics are non-biodegradable (cannot be broken down by decomposers)

Detrivores and Decomposers occur at all levels of the food web

Food Chains A food chain shows the flow of energy from producers to consumers Trophic level (aka: feeding level) is the position the organism occupies in the food chain Each trophic level helps ID the organism’s niche or role in the ecosystem

Ferns  Crickets  Snakes  Eagles Trophic Levels Term Primary Producer Primary Consumer Secondary Consumer Tertiary Consumer Example Plants Herbi or omnivores Omni or carnivores Ferns  Crickets  Snakes  Eagles

Energy Flow Plants use energy to produce carbohydrates (+ other organic molecules) in a process called photosynthesis

Energy Flow These carbohydrates (sugars) are used as energy by plants as well as consumers that eat plants

Energy Flow All consumers store excess energy as glycogen (carbohydrate), fat, and protein Omnivores and carnivores can get their energy by eating other consumers (animals)

Energy Flow Most organisms on the Earth get their energy either directly or indirectly from the sun

Ecological Pyramids

Ecological Pyramids Pyramid of energy – the 90%/10% rule Only 10% of the available energy is transferred from one trophic level to the next 90% of the energy an organism takes in is used for growth and repair or lost as heat

Ecological Pyramids 90%/10% rule is why many food chains have a maximum of 5 trophic level

Spent on Food Spent on Food Spent on Food Spent on Food Owner Editors Reporters Spent on Food Mailroom Spent on Food

Ecological Pyramids - Example Wolf eats a deer but does not consume all deer parts + some of the food eaten is eliminated as waste Therefore, the wolf only gets a portion of the available energy from the deer The energy the wolf does get is used to keep the wolf alive, to maintain its body temperature, and some energy is lost as heat

Pyramid of Biomass and Numbers

Pyramid of Biomass and Numbers As you move up the food chain there are fewer organisms. Because energy is lost at each trophic level Less energy available at each level means that fewer individuals can be supported

Pyramid of Biomass and Numbers As you move up the food chain there is less biomass Total mass of all organisms at the trophic level drops the higher up the food chain you go