Ocean Food Chains
Describe a simple ocean food chain: tiny plants (phytoplankton) are eaten by small animals, which are eaten by bigger fish, which are eaten by top predators like sharks, showing that all ocean life depends on others for food
What a learner can do afterwards
- Describe a food chain with at least three levels
- Identify that ocean food chains start with tiny plants or algae
- Explain that bigger animals eat smaller ones in a chain of dependence
1 · Read
Every ocean animal needs food. Food connects them in a chain. Tiny plants start every ocean food chain.
Tiny plants called phytoplankton float in the water. Small fish eat the phytoplankton. A big fish eats the small fish. A shark eats the big fish.
Every animal in the chain needs the one before it. If tiny plants disappear, the whole chain breaks.
Tiny plants feed small fish, which feed big fish, which feed sharks.
More to read
How an Ocean Food Chain Works
Every ocean food chain starts with tiny plants called phytoplankton. They float near the surface and use sunlight to make their own food, just like land plants. Small animals like zooplankton eat the phytoplankton. Small fish eat the zooplankton. Bigger fish eat the small fish. Top predators like sharks, tuna, and orcas eat the bigger fish. Energy passes from one level to the next, but only about ten percent moves up each step. That is why there are fewer top predators than tiny plants. If you take away the phytoplankton, the whole chain collapses. Decomposers like bacteria break down dead organisms and return nutrients to the water for phytoplankton to use again.
Who Eats Who in the Ocean?
Phytoplankton are the grass of the sea. They are so small you need a microscope to see them, but together they make more oxygen than all the forests on land. Zooplankton are tiny animals that drift with the currents. Copepods and krill are common zooplankton. They are food for fish, whales, and seabirds. Small fish like anchovies and sardines eat zooplankton. Tuna, sharks, and dolphins eat the small fish. Orcas are at the top. They eat fish, seals, and even other whales. People are part of ocean food chains too when we eat fish. Overfishing can break the chain and affect all the other animals.
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2 · Watch
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Where it sits
Learn first
Nothing; this is a starting point.
Optional connections
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Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.