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