Predators and prey
In this learning sequence, explore feeding relationships between Antarctic animals. Find out which animals share the same food source and compete for food. Explore predator-prey relationships and discover which animals go from being the predator to being the prey. Use food chains to demonstrate feeding relationships. Look at how the Antarctic changes during winter and summer and how this affects the abundance of food. Learn more about how and why scientists study penguins. Create a presentation about Antarctic life.
Setting the scene
A marine ecosystem
Pose the question: What do animals feed on in the Antarctic?
Show students the gallery of Antarctic marine ecosystem life. Discuss each living thing, enabling students to share what they know about each one and raise any questions. List questions which can be answered through the inquiry.
Ask students to create a scene of the Antarctic and use the images to show what each animal needs to survive, using the Antarctic marine ecosystem worksheet [PDF]. Use their drawings to assess what students know about what each animal feeds on, predator-prey relationships and food chains.
Complete the scenario
As a means of further assessing students’ prior knowledge about the diet and feeding habits of Antarctic animals, present some scenarios for students to consider, using the Living in Antarctica worksheet [PDF]. For each scenario ask them to write or explain what might happen.
The task may reveal:
- Organisms with which they are unfamiliar
- Animals whose diet they are unsure about or even that they are unaware that animals have a specific diet
- That they are unaware of the two types of whale; baleen and toothed whales and their different diets
- That they are unaware that marine plants need the sun to make their own food and are important to all animals directly or indirectly.
Explore and research
What’s for lunch?
Group students in pairs and give them an Antarctic animal to research. Their task is to find out what their animal eats. Ask them to print or draw an image of their animal and what it eats. They could also note any information about how the animal feeds and any special structures it has to catch its food.
Antarctic animals include:
- Seals: Ross, Weddell, crabeater, leopard, fur and elephant
- Whales: toothed whales (orca) and baleen whales (blue whale, fin, southern right whale, sei, minke and humpback)
- Penguins: Adélie, emperor, chinstrap and gentoo.
- Sea birds (flying): Black-browed albatross, Antarctic petrels, south polar skua
- Zoo plankton: krill (small shrimp-like crustaceans)
- Cephalopods: squid
Provide students access to the Australian Antarctic Division website wildlife section. For each animal, refer to the information provided under the sub-heading ‘Diet and feeding’.
Help with any unfamiliar scientific names for example diet may be identified using the scientific group name of animals for example cephalopods which includes octopus, squid and cuttlefish.
Make a class display of the information. It may help to group the images by animal type. Look for animals:
- that share the same food (competition)
- of the same type that feed on something different
- animals that are prey of other animals (predators)
- are scavengers (feed on dead animals)
- that feed on marine plants
Make some generalisations about feeding relationships. Also highlight where and why there are differences between different species within particular animal groups.
Explain and share
Review the class display showing what Antarctic animals feed on.
Use the display to pick out an animal to show how it is linked to other animals through what it eats and what eats it.
Explain how a food chain can show the feeding relationship between animals. Note that the direction of the arrow is from the food source to the animal that feeds on it. The direction of the arrow indicates the flow of energy from one organism to another.
A simple food chain is:
phytoplankton → krill → blue whale
Explain that in this example krill and the blue whale are consumers. Phytoplankton is a producer (plant). Most food chains start with a producer. Krill is a first order consumer and the blue whale is a second order consumer.
Guide students to create their own Antarctic food chains for the animal they researched, using the Antarctic food chains worksheet [PDF].
Discuss competition for food and predator-prey relationships. Identify producer and consumers.
Discuss the term abundance and what it means. Krill is the most abundant animal in the Antarctic. Group all the animals together that feed on krill. Make some generalisations about the importance of krill to the animals that depend on it for their food source.
Elaborate and apply
What’s special about Orcas?
Ask students to compare an orca (killer whale) to a blue whale. Use a Venn diagram to show what they have in common and what is different about them.
- hunting and feeding in packs/living alone or in a family group
- whale types (toothed and baleen)
- how baleen works to trap and filter whales’ food
- whales’ size and the amount of food they require per day
Summer and winter
Discuss the effect of having extended daylight in summer. How would that impact phytoplankton growth? How would that in turn effect the abundance of krill? What does this mean for other Antarctic animals? Make the connection between daylight hours, increased temperature and migration of animals to Antarctica.
Discuss the effect of having winters with minimal hours of daylight. Phytoplankton growth is affected by lack of sunlight and extremely cold temperatures. What do animals do to survive for food? Which animals stay during an Antarctic winter?
Find out what happens to krill numbers and where they go in winter.
Ask students to create two scenes; one of winter, the other summer. Show how life in Antarctica changes between the two seasons.
Ask students why scientists might study penguins.
Discuss and list approaches scientists might use to find out what penguins eat and where they go to find food (forage). Show the video clip on this page about Tracking emperor penguin chicks.
Discuss the benefits of satellite technology.
For further background information and an article to view using a guided reading approach, refer to: Satellite tracking.
Discuss how scientists use an automated weighing device to measure the weight of penguins as the leave a colony and then return after foraging for food.
Interpret the graph in the article showing the arrival and departure weights of tagged penguins. What does it reveal about their foraging? Discuss and clarify the terms outbound and inbound. Which term refers to going out to forage for food? Which term refers to returning after being out to forage for food?
Create your own presentation
Ask students to view their initial diagram of an Antarctic scene. Ask them to reflect on their learning and list ideas they have revised or new learning. Discuss these with each student.
Organise students in pairs or small collaborative groups, to create a presentation about life in Antarctica. The presentation could be a slide presentation, video or take some other form.
The presentation could take on several topics:
- a narrative explaining daily life of animals, for example viewed through the eyes of an Antarctic animal
- a scientific report predicting the impact on animals when there is a reduction in animal numbers of a particular species, including headings such as: my chosen animal, diet and feeding, threats to their food source.
- how life changes in the Antarctic from winter to the onset of summer. Which animals return when the days are longer and the temperature is milder?
At various points in the learning assess to what extent students:
- use a food chain to explain Antarctic animal feeding relationships
- identify competition between Antarctic animals
- identify predator-prey relationships
- describe the effect on animals when their food supply is reduced