Food Chains
• Food chains show which organisms eat
other organisms
Grass
Rabbit
Fox
• The arrows show the transfer of
energy from one organism to the
next.
• Producers - organisms which can make
their own energy from carbon dioxide and
water using sunlight for energy (plants)
• Primary consumer - organisms which eat
producers (herbivores)
• Secondary consumers - organisms which
eat primary consumers (carnivores)
• Tertiary consumers - organisms which eat
secondary consumers (carnivores)
• Each level of a food chain is known as
a trophic level
• Food chains always start with a
producer. Producers are always on the
first trophic level.
Food Chains
Each level of a food chain is known as a
trophic level
Tertiary consumer
Secondary consumer
Primary consumer
Producer
Barn owl
Fourth trophic level
Wood mouse
Third trophic level
Bark beetle
Oak Tree
Second trophic level
First trophic level
Food Web
Food Web
Great White Shark
Blue Regal
Clown Fish
Zooplankton
Small
Invertebrates
Sea Turtle
Algae
1. Write down two food chains from this food web.
Questions
1. What will happen to the number of clown fish if the sharks
become vegetarian?
2. What effect will this have on the number of zooplankton?
3. What will happen to the Blue Regal fish if a disease wipes out
the small invertebrates.
Food Web
Great White Shark
Blue Regal
Clown Fish
Zooplankton
Small
Invertebrates
Algae
Sea Turtle
Pyramids of Number
• Food chains and food webs show the
feeding relationships in a community. But
they do not tell us how many living
organisms are involved.
• It takes many plants to feed a herbivore,
and many herbivores to feed one carnivore.
On the coral reef, there are 25 great white
sharks.
These 25 sharks feed on 1,100 clown fish.
The clown fish feed on 15,000 algae.
Can you draw a pyramid of numbers to show
this food chain? Use a scale of 1 mm for each
100 organisms to draw the pyramid to scale.