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:1. The organism obtains food energy from the

ecosystem2. The organism contributes energy to the ecosystem

Food WebsHerbivores – eats plantsCarnivores – eats animalsOmnivores – eats plant and animalsInsectivore – eats insects

Top predatorTop 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 wasteDetrius – 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

Trophic LevelsTermPrimary ProducerPrimary ConsumerSecondary ConsumerTertiary Consumer

ExamplePlantsHerbi or omnivoresOmni or carnivores

Omni or carnivores

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 FoodPLANTS

Spent on Food

Spent on Food

Spent on Food

CRICKETS

SNAKES

EAGLES

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