Elakha. Phtot courtesy of the Elakha Alliance.
Overview
Lesson 1: Introduction to Relationships between Humans and the Environment
Lesson 2: Keystone Species and the Food Web
Lesson 3: Native Americans, Science, and Salmon
Lesson 4: Native Americans and Science
Lesson 5: Dangers to Sea Otter and Responsibility of People
Extending the lessons/References
Standards
LIFE SCIENCE
SC.05.LS.05—Describe the relationship between characteristics of specific habitats and the organisms that live there.
SC.05.LS.05.02—Identify the producers, consumers, and decomposers in a given habitat.
SC.05.LS.05.03—Recognize how all animals depend upon plants whether or not they eat the plants directly.
CD Segments to Play
Background
The plant leaf uses the sun’s energy and uses the nutrients, water and carbon dioxide to make carbohydrates (a carbohydrate is stored chemical energy, commonly called a calorie).
The root of the plant (like a straw) sucks water and nutrients from the soil.
Decomposers living in or on top of the soil break down plant material into nutrients; they need to have energy to do so.
The sun is the only source of energy for life to exist. Without the sun, the plants could not change carbon dioxide into oxygen that we need to breathe. Without carbohydrates, no living organism can survive.
When scientists conduct experiments over and over again with the same results, these are called laws (this is not a common occurrence). Thermodynamics is an area that has been extensively studied and laws have been discovered. The first law states that energy cannot be created or destroyed. The second law states that when energy is changed, some energy is lost.
What this means is that the sun (the only energy source) has a limited amount of energy. All organisms in an ecosystem are connected in a food chain or food web. There are several trophic (energy) levels.
A trophic level describes the relationship between energy and how far away from the energy source the organism is (remember, this is the plants). There are five trophic levels:
Primary producer: these are the plants.
Herbivore: this is an organism that eats only plants.
Omnivore: this is an organism that eats plants and meat.
Carnivore: this is an organism that eats only meat.
Top carnivore: this is an organism that eats only meat, the term “top” means that it has no natural predator.
Plants are the only things that are able to convert the sun’s energy into a form that we all can use to survive. All other living organisms need to obtain the energy from plants or from other organisms that eat plants. The further away from the plant source, the more food the organism must eat to get enough energy to survive.
Activities
1. Research
To begin the lesson, introduce basic components of an ecosystem, the foundation for all life. The components of a simplified ecosystem are: nutrients, water, oxygen and the living organisms. Energy (from the sun) is the vital component that fuels the ecosystem. A very basic and easy to understand model of an ecosystem can be illustrated with a simple potted plant. Have the students think about the five components (nutrients, water, oxygen, living organisms, energy) and how they relate to the potted plant. Make five columns on the chalkboard labeled with the five components. Have the students make the same chart and follow along with you. (This Ecosystem model should be added to their Sea Otter Portfolio.) Ask the students how each of the other components relate to the potted plant.
| Nutrients | Water | Oxygen | Living Organism | Energy |
| X | X | X | Plant Leaf | Convert |
| X | X | Plant Roots | Use | |
| X | X | Decomposers (fungi and bacteria) | Use |
Explain to the class that plants make their own food with the assistance of the sun, water, nutrients and oxygen.
2. Discuss
Ask: How do sea otters fit into this system?
Sea otters are a living organism that eats only sea animals. Sea otters must eat about 25-30% of their body weight every day, an adult sea otter weighs between 45-60 pounds; so if a 60 pound sea otter ate 25% of its weight, it would need to eat 15 pounds of food every day.
Sea otters live in the ocean in an underwater forest called a Kelp Forest. A Kelp Forest looks like giant leaves, they grow from the bottom of the ocean all the way to the top. Kelp is actually giant seaweed, which is algae. In a kelp forest live different kinds of algae (besides the giant kelp).
Inside of the kelp forest live fish, sea urchins and other sea life. Sea otters like to live by the kelp forests. They roll around in the kelp leaves so they are all wrapped up when they rest!
Ask: Why do you think they wrap up in the kelp leaves?
The obvious answer is to keep warm, but scientists think it’s so they can sleep and not float away. Sea otters have the thickest fur of all sea animals—so thick their body doesn’t even get wet! Imagine this: sea otters have 850,000 to 1 million hairs per square inch of their body. To compare this to humans, we have about 20,000 hairs on our whole head! Now, that’s a lot of fur.
Lesson 2, Day 2
Standards
LIFE SCIENCE
SC.05.LS.05—Describe the relationship between characteristics of specific habitats and the organisms that live there.
SC.05.LS.05.02—Identify the producers, consumers, and decomposers in a given habitat.
ENGLISH LANGUAGE ARTS
EL.06.RE.20—Clarify understanding of informational texts by creating simple outlines, graphic organizers, diagrams, logical notes, or summaries.
CD Segments to Play
Background
The sea otter is considered a keystone species. A keystone species is a species that is so important to an ecosystem that when it is gone the entire ecosystem is at risk. As you heard in the Wisdom of the Elders segment, from the early 1700s until a law was passed in 1911 that made it against the law to kill sea otters, fur traders killed sea otters to the point of near extinction. As the sea otter population got smaller, the sea urchin population grew and grew because there was nothing to eat the sea urchins. As a result, the kelp forests were eaten up by the sea urchins. What is left behind is called an urchin barren. When kelp forests disappear, there is no habitat or shelter for the fish and other sea animals that need the kelp forest to survive. Another thing that happens is that because the kelp is gone, there are no plants to convert the sunlight into a useable form.
The ban on killing sea otters saved the populations that lived in Alaska, but the sea otters that once lived up and down the coast of the Pacific Ocean were gone. In 1938, a small group of sea otters were seen near Carmel, California. Scientists began watching changes in the ecosystem. The sea otters began eating the sea urchins and the kelp forests began coming back. Along with the kelp forests came fish species that needed the kelp forests. There are many groups of people—Native American tribes, scientists, universities and others interested in bringing back the sea otter—that work together trying to help the sea otter populations come back. Recently a few sea otters were seen off the Oregon coast. This was great news! Scientists and other interested people are all working together to try to help the sea otters re-populate areas where they once lived.
Suggested Strategies
In preparation for the second day of the lesson, you will need to get small balls of string, one ball for each paired-up student.
Activities
1. Discuss
Ask: What do you think that sea otters eat? Have them look at their word search for help.
Sea otters eat abalone which lives on the sides of rocks. They love to eat sea urchins which live in the kelp forest. They also like clams, crab, turban snails, mussels, shrimp, octopus and fish.
Ask: Remember the energy chart we made yesterday, if the sea otter only eats sea animals, what does that mean about the sea animals?
All of the sea animals must eat plants or other animals that eat plants to survive.
2. Play a game
The Food Web Game
Write four living organisms on the board: sea otter, sea urchin, fish, and kelp.
Pair the students up, and divide the pairs equally between the four organisms. Have each student write the name of their organism and place it on their shirt. Have the pairs of students stand in a circle, each pair gets one ball of string.
Tell the students who eats who:
a. Sea otter eats sea urchin and fish, but their favorite food is the sea urchin.
b. Sea urchin eats kelp.
c. Fish eat smaller fish and algae (kelp).
d. Kelp converts sunlight to energy.
Have one of the pair begin. One student holds the ball of string and walks over to something it would eat and wraps the string around one of the students and returns to partner. The student in the pair that did not get wrapped with string looks for something to eat and walks over and encircles its prey and returns to starting point. It is very important that only one of the students gets encircled. As the predator/prey interaction continues, it will become more difficult for the student to maneuver under the strings. Continue the predator/prey interaction until each pair has had a turn. Tell the students that each pair represents an entire population, so they can get eaten more than once.
After all pairs have eaten, have the students look at the food web they have just created. Remind the students that many Native American Tribes consider all things are related to each other. Ask them if they can see by the food web how everything is actually related to each other and how dependent upon each other that the organisms are.
Now, have the students wrap up their balls of string and start over. But this time remove all of the sea otters from the group and have all of the sea otters become algae. All that should be left standing are the sea urchin.
3. Homework
If time permits, or as a homework assignment, have the students draw a food web and describe the impact that a keystone species has on an ecosystem. Add this to their Sea Otter Portfolio.
