Food Webs: Land and Water
Producers, Consumers, and Decomposers

Every living organism eats or
absorbs nutrients!

Plants absorb the sun’s energy and
carbon dioxide to make their own food
by photosynthesis.

An organism that makes its own food
is called a producer. All plants and trees
are producers.

Organisms that
cannot make their
own food must eat
other organisms to
obtain energy.

An organism that gets its food by
eating other organisms is a consumer.

Animals, many protists and some
bacteria are consumers.

A consumer that feeds directly on a
producer is a primary consumer (1st).

One that feeds on the primary
consumer is a secondary consumer
(2nd).

Then the animal that feeds on the
secondary consumer is a tertiary
consumer (3rd).

Most types of
fungus and many
bacteria are
decomposers.

A decomposer is
an organism that gets it
food energy by
breaking down the
remains of dead
organisms.

Decomposers are
important because they
recycle chemical nutrients back to the
environment.
Food Chains and Food Webs

The feeding levels of the producers
and consumers in an environment are
called trophic levels (energy pyramid).

Organisms take in food and energy
from each trophic level.

Food chains show the flow of
energy from the producers to the
consumers and to decomposers.

*Arrows are used to connect the
organism that is eaten to the animal that
eats it.

*A food chain is always straight.

A food web is used to show how the
organisms are connected in the
ecosystem.

Food webs are used to connect the
organism that is eaten to the animal that
it eats.

*Food webs have arrows going every
direction.
Land and Water Food Webs

A terrestrial, or land based, food
web shows the feeding relationships in a
land ecosystem and a food web in water,
called an aquatic food web.

These webs are often interconnected,
meaning land animals can eat water
animals and water animals can eat land
animals.
Energy Flow

Energy is lost as you go higher in
trophic levels because each organism
uses energy for its life processes.

Only about 10% of the energy is
passed up to the next trophic level.

Energy pyramids show the decrease
in energy.
FOLLOW UP QUESTIONS:
1. Give three feeding relationships that might
connect a lake and a forest ecosystem.
Fish  raccoon bear
2. Which of these is a primary consumer?
grass
hawk
mouse
wolf
3. If the producers make 150,000 kilocalories
of energy, how much energy is available to
the third trophic level?
a. 15,000 b. 1,500
c. 30
d. 15
4. In this food chain what is the secondary
consumer?
Grass  cricket  frog  snake
a. snake
b. frog
c. cricket d. grass
5. Put a check under producer or
consumer to show each organism’s part in
the food chain.
Organism
Snail
Robin
Mouse
Grass
Fox
Rose
plant
Worm
Owl
Rabbit
Corn
plant
Frog
Cat
Squirrel
Raccoon
Deer
Food Source Producer Consumer
Leaves
X
Worms, seeds
X
Seeds, beetles
X
Photosynthesis X
Rabbits
X
Photosynthesis X
Rotting leaves
Frogs, mice
Plants
Photosynthesis X
X
X
X
Worms, flies
Mice, birds
Nuts, snails
Berries, fish
grass, shrubs
X
X
X
X
X