Trophic Levels – is the position an
organism occupies in a food chain. It
refers to food or feeding.
Apex predator – top level predators with
few or no predators of their own.
Detritavore – feeds on dead organisms,
helps with decomposition
Review Vocab – carnivore, omnivore,
herbivore, scavenger, decomposer
The energy flow from one trophic level to the
other is know as a food chain
Producers are at the first TROPHIC LEVEL
Primary Consumers are the SECOND TROPHIC
Secondary consumers are at the THIRD
Tertiary consumers are at the FOURTH
In some ecosystems you can go out to
If an organism that lives in a terrestrial
ecosystem consumes an organism in an
aquatic (or aquatic to terrestrial) energy is
transferred between the two.
Ex. Bear eats a fish (energy from aquatic
to terrestrial) or fish eats a caterpillar
(energy from terrestrial to aquatic)
Transfer of Energy
When a lion eats a zebra, it does
not get all of the energy from the
Energy lost is usually in form of heat
Energy lost from chain “link” to “link”
from grass to sheep, loss is about
Energy! 1% Original
Energy lost from one trophic level
(energy level) to the next level can be
represented by a pyramid
♦ Each level above only gets 10% of the
energy from below
− Ex: 10,000 J of producers (plants) only give 10% of
energy to primary consumers
> 1,000 J to primary consumers (snails,
> 100 J to secondary consumers (small fish)
> 10 J to tertiary consumers (big fish)
> 1 J to quaternary consumers (fish hawk)
Three hundred trout are needed to
support one man for a year. The trout, in
turn, must consume 90,000 frogs, that
must consume 27 million grasshoppers
that live off of 1,000 tons of grass.
-- G. Tyler Miller, Jr., American Chemist
Usually no more than 5 trophic
levels since 6th level would have
very little energy to keep it alive
• Which level has the most energy?
• Which level has the most organisms?
• Which level has the least organisms?
• Which level has the least energy?
Pyramid of Numbers
• Shows the numbers of individual organisms at each
trophic level in an ecosystem.
• A vast number of producers are required to support even a few
top level consumers.
• Biomass is a measure of the total dry mass of
organisms in a given area.