Energy Flow in Ecosystems STANDARDS: 6 (e & f) e. Students know a vital part of an ecosystem is the stability of its producers and decomposers. f. Students know at each link in a food web some energy is stored in newly made structures but much energy is dissipated into the environment as heat. This dissipation may be represented in an energy pyramid.
What kinds of relationships exist among the plants and animals that make up a community? Being the young scientist you are, use the following field data to draw a diagram of the following relationships between plants and animals:
Field Note 1 Field Note 1 - In the hot dry deserts where most of us would prefer not to live there are some large green plants that look very different from most of the trees and shrubs we are used to seeing. These plants do not have the usual branches, twigs, and leaves like most plants. In fact many of these plants have spines and thorns. In spite of their spiny armor and different appearance, insects, birds, and small animals have been seen eating various parts of the plants.
Field Note 1 - The arrow also means that the plant part eaten by the squirrel has energy and this energy is used by the squirrel. - The diagram shows a relationship among two of the organisms in this description. - The ARROW shows that the some part of the plant is EATEN by the squirrel.
Field Note 2 Field Note 2 - Some of the largest animals ever to live on earth have been observed eating only plants. Many of us have seen some of these animals at zoos or videos of them shown on television. As you may have guessed, elephants are part of this group of large plant eating animals. Although no one has ever seen dinosaurs actually eating, scientists have figured out that some of these huge extinct animals were plant eaters. Make a diagram to show the relationship between two of the organisms in this description. Use an arrow in your diagram.
Field Note 2 or Analysis: 1. What does the arrow mean? 2. What is similar in this description to the first field note? 3. Compared to the first field note what is different in this description?
Field Note 3 Some of the meat you buy at the grocery store is from animals that eat plants or seeds from plants. For example, hamburger meat is taken from cows which eat a plant we commonly call hay. Also, chickens and turkeys are fed seeds from plants. Make a diagram to show the relationship between two of the organisms in this description. Use an arrow in your diagram.
Field Note 3 Analysis: 1. What does the arrow mean? 2. What is similar in this description to the second field note? 3. Compared to the second field note what is different in this description?
Field Note 4 Most of the living organisms in lakes, rivers, and oceans are rarely seen or heard about. These organisms are invisible to the naked eye even though they float at or near the surface. These organisms need light and other substances to survive. They come in a variety of colors but most are green. If you take a sample of water and observe these organisms under a microscope you will often see other small organisms eating them. Interestingly, very large animals such as whales also eat these organisms. Make a diagram to show the relationship between three of the organisms in this description. Use an arrow in your diagram.
Field Note 4 Analysis: 1. What does the arrow mean? 2. What is similar in this description to the third field note? 3. Compared to the third field note what is different in this description?
Field Note 5 Yellowstone National Park contains many hot water springs. Often the hot water jets out of these springs high into the air. There are several kinds of very small organisms that are able to live in these hot springs. Many of these organisms are green or bluish green and grow into long slender threads that are visible with the naked eye. Flies are often seen eating the organisms that make up the long slender threads. Make a diagram to show the relationship between two of the organisms in this description. Use an arrow in your diagram.
Field Note 5 Analysis: 1. What does the arrow mean? 2. What is similar in this description to the 4th field note? 3. Compared to the 4th field note what is different in this description?
Constructing a Model Replace words for pictures. Make a diagram using words and an arrow showing the relationships among the organisms in the different field notes. Use a single word for the organisms on each side of the arrow. Hint: What role are the “actors” / organisms playing? Producer Consumer Producer = An organisms that creates its own food Consumer = An organism that can not create its own food
The Sun is Earth’s source of Energy. It enters as high-grade light energy. And leaves us as low-grade heat.
* * * Let’s revisit the Field Note 3 and examine how energy is lost as energy flows between the sun, plants/seeds, and chickens: - We know that only 1% of the sun’s energy reaches living organisms. 99% energy lost 1% transferred to plants - The plants grow and produce seeds, which chickens eat. Notice how energy is lost as heat. Energy lost as heat
A true energy flow looks likes this: Heat Heat - Notice the Arrow. What does the arrow stand for? - If the arrow is smaller , what does that mean? If this energy flow continued, we humans would receive even less energy: Heat Heat
- As we see, energy is lost as heat as energy transfers from one organism to another in a food chain. In the Arctic, Eskimos hunt whales for food. Whales eat tons and tons of microscopic plankton. This plankton in turn eats microscopic algae. It requires 1,000 units of energy (calories) of algae to produce 100 calories of plankton which is what a whale uses to produce 10 calories of blubber (fat) to its body. Finally these 10 calories of whale blubber contains enough energy to give the Eskimo one calorie of energy. - Field Note 6 Analysis: - What percentage of energy IS being transferred between organisms?
- Second Law of Thermodynamics - - Scientists have studied many ecosystems and have concluded that this energy loss is a constant pattern. In fact, scientists have calculated that the percentage (%) of usable energy transferred from one organism to another is 10%. - That means that 90% of energy is lost as heat !!!!! - So…. if producers captured 10,000 calories from the sun, then only bout 1,000 calories will be available to support primary consumers (herbivores), and only about 100 calories to support secondary consumers (herbivores or omnivores). Producers 10,000 calories 1 0 Consumers 1000 calories 2 0 Consumer 100 calories Heat Heat
- The Pyramid of Energy Flow - - Energy flow and loss can be best viewed through the the Pyramid of Energy Flow. Energy pyramid principle This relationship can be shown using the following symbols. Producers energy > 1 0 consumers energy > 2 o consumers energy > 3 0 consumers energy, or Prod. cal. >1 0 cal. >2 0 cal. >3 0 cal. Another way to show this relationship is by constructing an energy pyramid, as shown below: Producers energy 1 0 consumer energy 2 0 energy 3 0 energy
- Just like a skyscraper has floors, or levels, an energy Pyramid has distinct levels, called TROPHIC LEVELS. Trophic Level = Feeding Level Trophic Levels Producers energy 1 0 consumer energy 2 0 energy 3 0 energy 1 st Trophic Level 2 nd Trophic Level 3 rd Trophic Level 4 th Tr. Level
A healthy ecosystem will always have the most energy available in the first trophic level. Algae 1000 calories Plankton 100 calories Whales 10 calories Eskimos 1 calorie Use the Food Chain in Field Note 6 to fill in this Pyramid of Energy 1 st Trophic Level 2 nd Trophic Level 3 rd Trophic Level 4 th Tr. Level
Field Note 7 - An ecologist surveyed an ecosystem to determine if it was healthy and sustainable. He spent a considerable amount of time identifying the organisms and determining their relationships. One of the food webs he identified is drawn below. The table contains the estimated energy of the organisms in the food web. Mice Snakes Hawks Rabbits Shrubs Grass
Field Note 7 The table contains the estimated energy of the organisms in the food web. To help you, add together all the Producers, 1 o Consumers, etc: Total energy for Producers = ____________ Total energy for 1 o Consumers = ____________ Total energy for 2 o Consumers = ___________ 3 o Consumer 1 o Consumer Explain in writing whether or not this ecosystem is in balance and therefore healthy and sustainable. Justify your explanation using the principles of an energy pyramid. Fill In Organism Energy (thousands of calories) Role Grass 800 Shrubs 200 Producer Rabbits 500 Mice 600 Snakes 0.5 Hawks 0.1