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 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 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

Trophic Levels

Term•Primary Producer•Primary Consumer•Secondary Consumer•Tertiary Consumer

Example•Plants•Herbi or omnivores•Omni 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 Food

Mailroom

Spent on Food

Spent on Food

Spent on Food

Reporters

Editors

Owner

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