Food Chains, Food Webs, and Ecological Pyramids
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The interactions that take place among biotic and abiotic factors lead to transfers of energy and matter. Every species has a particular role, or niche, in an ecosystem. Autotrophs are organisms that use energy from the sun or chemical energy to produce their own food. Autotrophs are also known as producers.
Heterotrophs are organisms that depend on other organisms for food. Because they consume rather than make food, heterotrophs are also known as consumers. A heterotroph that eats only plants is known as an herbivore. Heterotrophs that eat animals only are called carnivores. Omnivores are heterotrophs that eat both plants and animals. Also, scavengers are heterotrophs that feed on animals that are already dead. For example, vultures clean up the bodies of dead animals. Decomposers are consumers that break down dead or decaying organisms and absorb nutrients such as carbon and nitrogen from them. Decomposers are mainly bacteria and fungi that convert dead matter into gases such as carbon and nitrogen to be released back into the air, soil, or water. Decomposers are necessary since they recycle the nutrients to be used again by producers. Without decomposers, the earth would be covered in trash.
Food chains and food webs are pictures that show relationships among organisms. Each link in a food chain or web represents a feeding step or trophic level. The arrows in food chains and food webs show the direction of energy flow. That is, arrows point to the organism that receives the energy. Only about 10% of energy passes to the next level of a food chain. At each level, the other 90% of energy is “lost” to the environment as heat. Most food chains are only 3-4 links long because by the last link, only a smallportion of the original energy is left.
A food chain represents one possible path for the transfer of energy in an ecosystem. A food web shows many possible feeding relationships.
Heterotrophs are organisms that depend on other organisms for food. Because they consume rather than make food, heterotrophs are also known as consumers. A heterotroph that eats only plants is known as an herbivore. Heterotrophs that eat animals only are called carnivores. Omnivores are heterotrophs that eat both plants and animals. Also, scavengers are heterotrophs that feed on animals that are already dead. For example, vultures clean up the bodies of dead animals. Decomposers are consumers that break down dead or decaying organisms and absorb nutrients such as carbon and nitrogen from them. Decomposers are mainly bacteria and fungi that convert dead matter into gases such as carbon and nitrogen to be released back into the air, soil, or water. Decomposers are necessary since they recycle the nutrients to be used again by producers. Without decomposers, the earth would be covered in trash.
Food chains and food webs are pictures that show relationships among organisms. Each link in a food chain or web represents a feeding step or trophic level. The arrows in food chains and food webs show the direction of energy flow. That is, arrows point to the organism that receives the energy. Only about 10% of energy passes to the next level of a food chain. At each level, the other 90% of energy is “lost” to the environment as heat. Most food chains are only 3-4 links long because by the last link, only a smallportion of the original energy is left.
A food chain represents one possible path for the transfer of energy in an ecosystem. A food web shows many possible feeding relationships.
Food Chain Game and Quiz
Food Chain Models
In your journal, create an entry titled "Food Chain Models". Create the chart below.
Read the paragraphs below.
In the ocean, food chains begin with producers that are not plants. They are algae. Algae come in many forms but one common algae is seaweed. Seaweed is eaten by many first consumers such as shrimp. The shrimp are then food for many squid. The squid are preyed upon by sea lions and other sea predators. Finally the sea lions are eaten by very large predators such as the great white shark.
In the grassy plains of Texas, food chains begin with a logical source, grass! Grass is food for many first consumers such as grasshoppers. Grasshoppers reproduce very rapidly and can reach very large populations. They are food for many insect eating animals such as toads. Toads are very common in Texas plains because they can survive in much dryer ecosystems. Toads are preyed upon by many smaller predators such as the coral snake. The coral snake is a very unique snake with a red, yellow and black banded pattern. Coral snakes are eaten by birds of prey like owls and hawks.
In the springtime of Canada flowers bloom near rivers. These flowers produce a sweet smell and delicious nectar. This nectar may not be delicious to you and me but is a great food source for many insects such as flies. Flies are eaten by larger insect predators such as dragonflies. Dragonflies are common on the waters of a flowing river. But, lurking below the surface is a host of hungry fish. Salmon in particular eat insects that get to close. Salmon grow to enormous sizes and can reproduce quickly. In the summer and early fall, Grizzly Bears can be seen in the river catching salmon; getting fat for their long winter slumber.
Use the information from the reading assignment to complete your chart. The three respective food chains should be completed using the steps below.
In the ocean, food chains begin with producers that are not plants. They are algae. Algae come in many forms but one common algae is seaweed. Seaweed is eaten by many first consumers such as shrimp. The shrimp are then food for many squid. The squid are preyed upon by sea lions and other sea predators. Finally the sea lions are eaten by very large predators such as the great white shark.
In the grassy plains of Texas, food chains begin with a logical source, grass! Grass is food for many first consumers such as grasshoppers. Grasshoppers reproduce very rapidly and can reach very large populations. They are food for many insect eating animals such as toads. Toads are very common in Texas plains because they can survive in much dryer ecosystems. Toads are preyed upon by many smaller predators such as the coral snake. The coral snake is a very unique snake with a red, yellow and black banded pattern. Coral snakes are eaten by birds of prey like owls and hawks.
In the springtime of Canada flowers bloom near rivers. These flowers produce a sweet smell and delicious nectar. This nectar may not be delicious to you and me but is a great food source for many insects such as flies. Flies are eaten by larger insect predators such as dragonflies. Dragonflies are common on the waters of a flowing river. But, lurking below the surface is a host of hungry fish. Salmon in particular eat insects that get to close. Salmon grow to enormous sizes and can reproduce quickly. In the summer and early fall, Grizzly Bears can be seen in the river catching salmon; getting fat for their long winter slumber.
Use the information from the reading assignment to complete your chart. The three respective food chains should be completed using the steps below.
- Obtain the food chain matching cards below from your instructor.
- Cut and paste the pictures in the appropriate spaces on your chart based on the information in the reading passage.
- Write the names of the organisms above each picture.
- Add arrows between the pictures of the organisms to represent the flow of energy.
Food Web Analysis
Create an entry in your journal titled "Food Web Analysis". Create the chart below in your journal.
Identify the food chains represented in the food web below. Complete one row in your chart for each food chain that is identified. Write the names of the organisms in the food chain in the appropriate trophic levels. Indicate the amount of energy available at each trophic level in the last row.
Brain Pop Quiz - Food Chains
Log into Brainpop.com and take the Food Chain Video Quiz. Take the Graded Quiz. If you have not yet signed up for a Brainpop account, see your teacher for instructions.
Ecological Pyramid
Obtain the following pyramid template from your instructor.
Create model pyramid according to the instructions below.
1. Shade the first (bottom) level of each pyramid green.
2. Shade the second level of each pyramid yellow.
3. Shade the third level of each pyramid blue.
4. Shade the fourth (top) level of each pyramid red.
5. Label each level of the first pyramid side with the following terms as you move up the pyramid: producer, primary consumer, secondary consumer, tertiary consumer.
6. Label each level of the second pyramid side with the following terms as you move up the pyramid: plants, herbivores, carnivores, top carnivores.
7. Label each level of the third pyramid side with the following terms as your move up the pyramid: autotroph, 1st order heterotroph, 2nd order heterotroph, 3rd order heterotroph.
8. Draw a picture of what might belong in each level:
1st: flowers, trees, grass, algae
2nd: caterpillars, cows, grasshoppers, beetles
3rd: humans, birds, frogs
4th: lions, dogs, snakes
9. Fold your pyramid on the lines radiating from the center and staple it together.
Ecosystems, Organisms and Trophic Levels Lab
What Is Ecology About Anyway?
Ecology is the relationship of living things to each other and to what’s around them. So, if you are learning about what kinds of relationships fish have with other animals (including us!) and plants in their neighborhood, then you are learning about ecology.
The word ECOLOGY comes from Greek words meaning “study of the household.” That means that ecology is the study of the “household” of living things: their neighbors and neighborhood.
Ecology includes not only how living things interact with each other, but how they interact with their physical environment: things such as climate, water, and soil. Both nonliving and living organisms come together to form what we call an ecosystem which is a biological community of interacting organisms and their physical environment.
One type of organism is called a producer (also know as an autotroph) which has the ability to convert solar or chemical energy into a useable form of energy. The most common producers are plants that use the process of photosynthesis to convert solar energy into glucose, which can be consumed and used by other organisms. These organisms that feed on or consume other organisms are called consumers (also known as heterotrophs) which must get their energy from other organisms.
Heterotrophs are the most diverse group because there are many different ways in which to consume food. The first group is known as carnivores, which is a group that feeds only on other organisms and not on producers (think of them as meat eaters). An example of a carnivore is a lion which feeds primarily on other organisms such a zebra or wildebeests. The second group is called herbivores because they feed only on producers (including plants). An example of an herbivore is cattle or horses that depend on grains and grasses. The last group is a mixture of the two and is called omnivores because they feed on both other organisms and producers. An example of an omnivore is a human being or bears which can eat both meats and plants. Another type of heterotrophs is called a detrivore, and these organisms feed on dead or decaying matter. One type of detrivore is a scavenger which moves around feeding on dead material, and includes organisms such as coyotes and vultures. The other type of detrivore is a decomposer that grows on dead or decaying matter, and includes organisms such as fungi and bacteria.
Ecologists are the scientists who study ecology. They are curious and like to learn about living things by observing them, seeing what happens, and recording what they find. This is all part of the scientific method.
Some ecologists study a specific species or habitat. The habitat is the natural home or environment of an animal, plant, or other organism. Within a habitat, there are several populations, which are a specific group or type of animals or organisms living within an area. They might study the behavior of a single species to see how it interacts with other organisms and the environment. Or, an ecologist might study many different species that either depend on each other (a food web, for example), or compete with each other for food and space.
The word ECOLOGY comes from Greek words meaning “study of the household.” That means that ecology is the study of the “household” of living things: their neighbors and neighborhood.
Ecology includes not only how living things interact with each other, but how they interact with their physical environment: things such as climate, water, and soil. Both nonliving and living organisms come together to form what we call an ecosystem which is a biological community of interacting organisms and their physical environment.
One type of organism is called a producer (also know as an autotroph) which has the ability to convert solar or chemical energy into a useable form of energy. The most common producers are plants that use the process of photosynthesis to convert solar energy into glucose, which can be consumed and used by other organisms. These organisms that feed on or consume other organisms are called consumers (also known as heterotrophs) which must get their energy from other organisms.
Heterotrophs are the most diverse group because there are many different ways in which to consume food. The first group is known as carnivores, which is a group that feeds only on other organisms and not on producers (think of them as meat eaters). An example of a carnivore is a lion which feeds primarily on other organisms such a zebra or wildebeests. The second group is called herbivores because they feed only on producers (including plants). An example of an herbivore is cattle or horses that depend on grains and grasses. The last group is a mixture of the two and is called omnivores because they feed on both other organisms and producers. An example of an omnivore is a human being or bears which can eat both meats and plants. Another type of heterotrophs is called a detrivore, and these organisms feed on dead or decaying matter. One type of detrivore is a scavenger which moves around feeding on dead material, and includes organisms such as coyotes and vultures. The other type of detrivore is a decomposer that grows on dead or decaying matter, and includes organisms such as fungi and bacteria.
Ecologists are the scientists who study ecology. They are curious and like to learn about living things by observing them, seeing what happens, and recording what they find. This is all part of the scientific method.
Some ecologists study a specific species or habitat. The habitat is the natural home or environment of an animal, plant, or other organism. Within a habitat, there are several populations, which are a specific group or type of animals or organisms living within an area. They might study the behavior of a single species to see how it interacts with other organisms and the environment. Or, an ecologist might study many different species that either depend on each other (a food web, for example), or compete with each other for food and space.
Make a Food Web
Procedure:
1. Use scissors to cut the pictures apart.
2. Sort the pictures into groups according to energy sources; producers, herbivores/primary consumers, secondary consumers, tertiary consumers, scavengers and decomposers.
3. Construct a food chain that might occur in the ecosystem. Draw arrows to show that energy is passed from one organism to another. Place the cut out on a sheet of paper, BUT DO NOT GLUE DOWN! (Arrows go from the animal that is eaten to the animal doing the eating).
4. Use the same pictures to form a food web by first arranging them on your desk. Remember that a food web is several food chains linked together. Construct a food web as it would occur in this ecosystem. Glue or tape your food web to the back of this sheet. Again draw arrows to show that energy is passed from one living organism to another.
5. Look at your food web. If any of your organisms have a box around them, they have been sprayed with an insecticide (bug spray that kills bugs) such as DDT, or have eaten an organism that has been sprayed with one of these compounds. If animals also eat the organism that has been sprayed, they take in the poison. The animals may not die, but the poison builds up in the organs of its body. Because larger animals eat more food that may be affected with the poison, more poison is naturally concentrated in the larger animal(s).
6. Take a colored pencil or canyon and mark all of the organisms in the food web that might get some of the poison into their bodies from their food.
1. Use scissors to cut the pictures apart.
2. Sort the pictures into groups according to energy sources; producers, herbivores/primary consumers, secondary consumers, tertiary consumers, scavengers and decomposers.
3. Construct a food chain that might occur in the ecosystem. Draw arrows to show that energy is passed from one organism to another. Place the cut out on a sheet of paper, BUT DO NOT GLUE DOWN! (Arrows go from the animal that is eaten to the animal doing the eating).
4. Use the same pictures to form a food web by first arranging them on your desk. Remember that a food web is several food chains linked together. Construct a food web as it would occur in this ecosystem. Glue or tape your food web to the back of this sheet. Again draw arrows to show that energy is passed from one living organism to another.
5. Look at your food web. If any of your organisms have a box around them, they have been sprayed with an insecticide (bug spray that kills bugs) such as DDT, or have eaten an organism that has been sprayed with one of these compounds. If animals also eat the organism that has been sprayed, they take in the poison. The animals may not die, but the poison builds up in the organs of its body. Because larger animals eat more food that may be affected with the poison, more poison is naturally concentrated in the larger animal(s).
6. Take a colored pencil or canyon and mark all of the organisms in the food web that might get some of the poison into their bodies from their food.