Name: Date: Aim: How does energy flow in Arctic and Antarctic ecosystems? Explore The four food webs are: o Antarctic Marine Food Web o Arctic Marine Food Web o Tundra Land Food Web o Tundra Freshwater Food Web Project Carefully follow the instructions below with your group. 1. Use the Food Web Cards to build the connections between organisms. Each card has the name and picture of an organism, and information about what the organism eats or is eaten by. Begin with the different types of organisms that use the Sun s energy to make food. Organisms that make their own food are called producers. Producers may be plants, phytoplankton or other organisms that do photosynthesis. Place these cards near the bottom of a blank piece of poster paper. Draw the Sun near the producers, and draw an arrow to show how the energy is transferred from the Sun to the producer. 2. Other organisms get energy from the producers. Organisms that eat other organisms are called consumers. Read through the cards and determine which consumers eat the producers. Place these cards on the poster above the producers and use arrows to show the flow of energy. 3. Continue to add the different cards to the poster and connect them using arrows. Remember that the arrows must show the direction in which the energy flows. There may be one or many arrows connected to a single organism. 4. Once all of the organisms are best connected, glue the Food Web Cards to the poster. 135
The diagram your group created represents the transfer of food energy within a community of organisms. It also shows the feeding relationships between organisms in an area. This diagram is known as a food web. Each food web consists of natural organisms that depend on one another. Unlike agricultural areas, which humans fertilize and tend, the food webs presented here are naturally and perfectly balanced due to interactions between the organisms and their environments. Explain Now, use the poster and the following information to answer the questions below: 1. What is the source of energy for this food web? What happens over the course of a year? 2. To what extent is this a complete food web? Explain. 3. How do these food webs change with the seasons? 136
4. In the Venn Diagram below, compare and contrast the Arctic and Antarctic food webs. 137
5. How do you think Alaska Native peoples and other Indigenous peoples across the circumpolar North would fit into these food webs. Give specific examples. We did not study a land food web in the Antarctic. Land organisms in the Antarctic include lichens, mosses, two types of flowering plants, insects such as midges, as well as bacteria. No land animals larger than a half centimeter long survive in the Antarctic. The largest land animal is a wingless midge called Belgica antarctica pretty small! Midge Adult. Credit: Susan Ellis, USDA APHIS PPQ, Bugwood.org 6. Why does there not exist a large land food web in the Antarctic as there is in the Arctic? (Hint: Consider what you learned in the previous lessons.) 138
Elaborate Life in the tundra sure isn t easy. All living things in the tundra, and, in fact, everywhere on Earth, have the same basic needs and must complete the same functions inside their cells. Resources, like water, shelter and food, are not unlimited. That means that many diverse organisms strive for similar resources; there is competition between organisms. Some groups of organisms compete more successfully than others and survive over time. Those groups and individuals that are not as successful do not survive and may even die out completely, or become extinct. Most organisms that have ever lived on Earth are now extinct. How do groups survive? Thank the lucky genes. Adaptations. Throughout the planet s history, Earth s diverse environments have changed a lot. Not every organism is equipped to survive environmental changes. Some organisms are born with lucky genes that give the organisms characteristics that make them more likely to survive in a specific environment. Of course, no organism lives forever. Each must reproduce to pass on its genes and ensure the survival of their group. When organisms reproduce, they pass on to their offspring the very characteristics that helped them to survive. Characteristics that enhance the survival and reproductive success of organisms are adaptations. Characteristics are only adaptations if they are in an organism s genes. Adaptations can take many forms, some of which are not visible. 139
Life in the tundra is very difficult. Over the millennia, many different adaptations have appeared in tundra plant species. Let s look at some examples. Keep it Low The tundra landscape is dominated by plants that are low to the ground. Many of them have small leaves. This structure protects the plants from the ice cold temperatures and the whipping wind that can pelt plants with particles of ice and snow. The small leaf structure prevents the plants from losing too much water from their leaves in the cold, dry, windy climate. In addition, tundra plants have shallow root systems. Recall that water in the soil stays above the frozen layer of the permafrost. The plant roots do not reach further down than this top layer. In fact, they can t because it is frozen. Many tundra plants also grow in clumps, or clusters, on the ground that look like cushions. Sometimes they are even called cushion plants. By growing close to the ground and tightly packed together, these plants are protected from the wind and the harsh temperatures. If you were to visit the tundra, you would also notice that producers grow in cracks in the rocks. One example is a special producer that is not a plant at all the lichen [pronounced LIEkin]. Lichens are made up of fungi (like mushrooms) and algae (like seaweed) or bacteria. The fungi and the algae or bacteria work together. The fungus breaks down rock or soil and provides nutrients to the algae or bacteria. This is especially important in places where there is little soil or the soil is frozen. Then, the algae or bacteria do photosynthesis, providing the fungus with the sugar it needs to survive. Lichens are an important food source for animals like caribou. Growing in the cracks of rocks is a good strategy because the lichens are protected from the wind. In fact, even the Dry Valleys of Antarctica, which are the coldest, driest places on Earth, have lichens living there. 140
Flower Quickly and Use Colors In the summertime, the tundra comes alive with beautiful wildflowers. These flowers have the unique ability to bloom quickly when light and water are available. When summer arrives and the top layer of soil thaws, the tundra landscape becomes very mushy. Plants take advantage of the available water and abundant sunlight remember that in the summer, the tundra gets light nearly 24 hours each day. Therefore, tundra plants have a very fast growing season. Producing flowers requires a lot of energy. However, when sunlight and water are plentiful, plants can make lots of them. In addition to beautiful flowers, some plants make brightly-colored berries. The flowers and berries attract birds and insects. Summer in the tundra results in the arrival of huge numbers of insects, including flies and mosquitoes. These insects carry pollen from plant to plant and also the seeds to new places. This ensures that the plants lucky genes are carried on to the next generation. Credit: T. Lee Tibbitts / USGS You might also notice that many tundra plants have red leaves. Leaves are where photosynthesis happens. Red leaves have less chlorophyll but can still accomplish photosynthesis. Scientists believe that the red pigment helps to absorb ultraviolet (UV) radiation, protecting the plant from UV damage. In other words, the red pigments act like sunscreen for the plant. This is a good adaptation in the Arctic summer where the sun shines on the plants 24 hours each day, 7 days a week. Use the Wind While many plants rely on birds and insects to distribute their seeds, others use the wind. In the tundra, the wind is nearly constant. Many tundra plants have very light, fine seeds that are easily carried by the wind. Once they land in a patch of soil, they can grow in a new place. One good example of a plant that uses this strategy is cottongrass. 141
7. Complete the chart below to describe how specific adaptations help tundra plants to survive and pass on their genes. Growing Low to the Ground Light Seeds Bright Colors Shallow Roots Red Leaves 8. What do tundra plants have to do with food? As Earth s Polar Regions warm with climate change, different species may be able to survive in areas where they couldn t before. For example, scientists and Indigenous peoples are noticing trees appearing in areas that were once dominated by grasses and shrubs. 142
Evaluate 1. Describe one difference between Arctic and Antarctic food webs. 2. Describe two adaptations that plants and animals in the Arctic and Antarctic may have. 3. Explain how energy is transferred from the Sun to a predator such as a polar bear. You may choose to use a picture to help explain your answer. 143