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Seaweeds use a process called photosynthesis to get their energy (food) from the sun.

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All organisms which photosynthesise are known as primary producers.

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Producers make their own food for energy

While consumers eat other organisms for energy

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Urchins are are herbivores and graze on seaweeds.

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As they only eat primary producers

urchins are known as primary consumers.

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Phytoplankton

Phytoplankton are tiny algae which live in the ocean which is also a primary producer which use photosynthesis to get their energy from the sun.

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Zooplankton (also known as “animal plankton”)

are also primary consumers as they eat phytoplankton.

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Some fish which eat seaweed too and are also known as herbivores.

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These primary consumers have a specialised digestion system that allows them to digest seaweeds.

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The energy from the sun, captured by the seaweed is transferred up the food chain.

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The energy from the sun, captured by the seaweed is transferred up the food chain.

Biologists use arrows to show the direction of flow of this energy.

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Secondary consumers eat herbivores

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Secondary consumers eat herbivores

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Predators may eat many different animals

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Predators may eat many different animals

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Rough rock crab

Nectocarcinus integrifrons

Some species are detritivores and may eat decaying plant and animal material

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Food chains show a single pathway that energy and nutrients may transfer through an ecosystem.

Food Chains

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Food chains show a single pathway that energy and nutrients may transfer through an ecosystem.

Food Chains

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Food chains show a single pathway that energy and nutrients may transfer through an ecosystem.

Food Chains

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Food chains show a single pathway that energy and nutrients may transfer through an ecosystem.

Food Chains

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Food chains show a single pathway that energy and nutrients may transfer through an ecosystem.

  • Trophic levels represent the position that an organism occupies in a food chain
  • Primary producers use photosynthesis to get energy from the sun.
  • Herbivores eat exclusively plants and algae
  • Primary consumers are herbivores and eat mostly plants or algae
  • Secondary consumers eat herbivores
  • Tertiary consumers eat carnivores
  • Detritivores eat decomposing matter

Food Chains

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Butterfly Perch

Caesioperca lepidoptera

Some species can be on multiple trophic levels.

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Food webs

Energy flow in an ecosystem and food web interactions.

Lesson 5

Primary

Producer

Primary

Consumer

Secondary

Consumer

Secondary

And Tertiary Consumer

Some species can be on multiple trophic levels.

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Biomass is the “living weight” in an area

There is always more biomass in lower trophic levels than in higher ones.

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Southern calamari

Sepioteuthis australis

At each level in the food chain, some energy is also released to the environment.

Only about 10 percent of the chemical energy is passed from one trophic level to the next.