ECOSYSTEMS – AN ANTARCTIC CASE STUDY
LESSON 1 AN INTRODUCTION TO ECOSYSTEMS, FOOD CHAINS AND FOOD WEBS LESSON 1 : AN INTRODUCTION TO ECOSYSTEMS, FOOD CHAINS AND FOOD WEBS
This organism is only about 50mm (2”) in length, but plays a giant part of life in marine ecosystems…
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Humpback whale Length from 12–16 m Weight 25–30 metric tons
…it is a bigger part of life in marine ecosystems than this organism.
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How can something so small be so important in a marine ecosystem?
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LESSON OBJECTIVES
Understand that food chains represent simple feeding relationships
Understand that food webs represent the complex feeding interactions within an ecosystem
Know that food chains always begin with a producer, and in the sea, this is often phytoplankton
Use a range of relevant, scientific vocabulary
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WHAT IS A FOOD CHAIN
A food chain shows the path by which energy transfers from one organism to another.
It shows how each organism is dependent on another as a source of food. phytoplankton krill Blue whale
shows the transfer of energy from one organism to another.
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FOOD CHAIN
phytoplankton krill Blue whale
Producer Primary consumers Top carnivore Autotroph Herbivore
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THE START OF A FOOD CHAIN
Food chains start with a producer, which is an organism that can produce its own food. On land, this is normally a plant but in the ocean this is often phytoplankton.
Phytoplankton are extremely small but are important because they are the start of most marine food chains.
Phytoplankton are plants. They use photosynthesis to produce their own food. Over half the world’s oxygen is produced by phytoplankton!
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IMPORTANT VOCABULARY
Phytoplankton: Producer: Small, often single-celled, Able to make its own food plants that can (photosysnthesise). photosynthesis (use the It uses sunlight, carbon dioxide sun’s energy to make and water. Producers are at food). the beginning of all food It cannot move by itself. chains.
Autotroph: Able to make its own food.
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IMPORTANT VOCABULARY
Primary consumer: Krill: A consumer is an organism Krill are small crustaceans and that eats another organism are found in all the world’s (consumes it). oceans. They are an extremely A primary consumer is the important part of Antarctic first organism in the food ecosystems because so many chain that eats another animals eat them. organism. In our food chain example, Prey: krill eats phytoplankton. Krill are eaten by many Antarctic organisms. In our food chain example they Herbivore: are eaten by blue whales. Herbivores are animals that Only 10% of energy is only eat plant, e.g. transferred from one organism phytoplankton. to another.
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IMPORTANT VOCABULARY
Carnivore: Secondary consumer: A carnivore is an animal The secondary consumer is the that eats other animals. third organism in a food chain. E.g. the blue whale eats It eats the primary consumer. krill.
Predator: A predator is an animal that eats another animals. The blue whale is a predator to krill.
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IMPORTANT VOCABULARY
Apex predator: Top carnivore: The apex predator is the The top carnivore is the predator at the top of the carnivore (eats animals) at the food chain. This means top of the food chain. that it has no natural predators.
Orca: Also known as killer whales, are found at the end of many food chains.
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IMPORTANT VOCABULARY
Decomposers: A decomposer breaks down or decomposes organic material such as the remains of dead organisms. These organisms carry out the process of decomposition. It is an essential role to help recycle vital nutrients back into the ecosystem. On land decomposers include worms, beetles, fungi and bacteria. Decomposition in Antarctica is often very slow. A common decomposer in the Southern Ocean is bacteria.
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YOUR TURN!
Demonstrate your understanding of the important vocabulary.
Take a marine organism card.
Match appropriate vocabulary from the vocabulary list.
Repeat with more marine organism cards until you have used up all the vocabulary words from the list.
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FOOD CHAINS COME IN DIFFERENT LENGTHS
phytoplankton krill Blue whale Energy transfer
phytoplankton krill penguin Blue whale
phytoplankton krill fish Leapord seal Blue whale
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YOUR TURN!
Have a go at making your own marine food chains.
Use the marine organism cards to make a food chain.
Remember to start with a producer and end with a apex predator.
Use the prey and predator information to help decide on your food chain.
Remember to point your energy transfer arrow in the right direction.
Extension: Can you make 3, 4, 5 and 6 organism food chains?
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FOOD WEBS
Food chains are really useful. BUT they don’t tell the whole story. You will have noticed from your marine organism cards, that organisms often eat more than one organism, and are often eaten by more than one organism. Krill, for example, is eaten by almost everything in Antarctica! When you put lots of food chains together, you can use more energy transfer arrows to show these more complex relationships. This is called a food web.
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FOOD WEB
In nature, most organisms eat more than one thing, and are often prey to more than one predator. A series of food chains within in an ecosystem that all interact is called a food web. Look at how this Antarctic food web is built up.
phytoplankton
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FOOD WEB
zooplankton krill
phytoplankton
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FOOD WEB
penguin Leopard seal
squid fish
zooplankton krill
phytoplankton
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FOOD WEB
Killer whale
Blue whale
penguin Leopard seal
squid fish
zooplankton krill
phytoplankton
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FOOD WEBS AND FOOD CHAINS
Lots of food chains make a food web, but you can still see the individual Killer whale food chains. Blue whale Write down three examples of food penguin Leopard seal chains from this food web.
Remember your energy squid fish transfer arrows.
zooplankton krill
phytoplankton
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FOOD WEBS AND FOOD CHAINS
You can pick out individual food chains from a food web. For example,
Phytoplankton krill baleen whale (e.g. blue whale)
Phytoplankton krill seal toothed whale (killer whale)
Phytoplankton krill fish leopard seal toothed whale (killer whale)
Image from http://science.jrank.org/kids/pages/63/FITTING-ALL-TOGETHER.html
IN PARTNERSHIP WITH SPONSORED BY LESSON 1 : AN INTRODUCTION TO ECOSYSTEMS, FOOD CHAINS AND FOOD WEBS
YOUR TURN!
Use your marine organism cards and energy transfer cards to create a food web.
IN PARTNERSHIP WITH SPONSORED BY LESSON 1 : AN INTRODUCTION TO ECOSYSTEMS, FOOD CHAINS AND FOOD WEBS
FOOD CHAINS – ASSESSMENT FOR LEARNING
Draw out this food chain. Add as may vocabulary labels as you can. 1 point for each word used correctly.
phytoplankton krill small fish Elephant seal
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WHAT DID YOU LEARN TODAY?
Understand that food chains represent simple feeding relationships Understand that food webs represent the complex feeding interactions within an ecosystem Know that food chains always begin with a producer, and in the sea, this is often phytoplankton Use a range of relevant, scientific vocabulary
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A food web shows how all the different food chains are connected and dependent on one another. This dependence on other living organisms is called interdependence.
This means, that changes to one species will have a knock-on effect to a number of other species.
We will look at this in our next lesson.
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