Earthworm Invasion (Part 2/2)
Lesson 5 of 12
Objective: Students will investigate a real-world example of interspecific competition.
Students will continue where they left off yesterday and complete the evaluation of the earthworm/millipede interspecific competition study. Using the distribution maps they generated as homework, they will determine if similar problems are happening in other parts of the United States. Then they will develop a plan to either prevent or control the spread of invasive earthworms. As homework, they will design an education campaign to inform the public of the problem. This is day two in a two day lesson. Here is an overview of what they will learn today.
Using student responses from yesterday, create a Wordle. Show the Earthworm Invasion Wordle to the class and ask them to explain how the terms interrelate. Give students several minutes to write a short summary about the Wordle.
Ask students to share the two worm species for which they made distribution maps. Focus first on the non-native worms and have students share what they hypothesized. For yesterday's homework, they considered the following questions:
- Hypothesize how they think the non-native worm got to that area of the state.
Possible student answers:
The non-native worm could have gotten to the area in a number of ways:
Cocoons could have been brought to the area on soil stuck to farm implements.
Mothers of little kids collecting worms could have dumped out their collection.
People fishing could have left the worms at the farm pond.
- Hypothesize how they think these non-native earthworms might change the environment in which they are now living.
Possible student answers:
They might out compete the native worms for food.
They might reproduce in larger numbers.
They might be less selective in the food that they eat.
Have students project their distribution maps that they created yesterday. As a class pick one more species of earthworm and complete a distribution map together. Using the data that students analyzed, determine as a class if there is a problem with invasive earthworms.
Ask students the following questions:
- Is there a problem with any particular species of non-native earthworms? Why or why not?
Possible student answers: It is very hard to tell because there is very little data and it is spread out all over the state.
Maybe not. There was not a lot of native worms in the areas sampled (Note: See close-up of student distribution map) either. Maybe worms there aren't that many earthworms.
- If there is not enough information to determine a trend, what needs to be done to collect more information?
Possible student answers: More detailed sampling will need to be done. After looking at the maps, I found that only one or two worms were found in certain areas. I know from personal experience that there are a lot more earthworms in an area because I used to dig them when I went fishing.
Maybe areas could be randomly sampled like we did with our plant study where we sampled certain areas for an invasive plant. We could dig holes in the ground and see what types of worms were there.
We need to sample more, but I'm not sure how to do it. I feel that just randomly digging might destroy the area. Is there a method that scientists use that makes the least damage?
Students should look at historic data for both native and non-native species to determine if life in the area has changed or could change due to the introduction of non-native earthworms. Students should pick one native species and one non-native species to research. After looking at the historic data, they should then determine if both worms were seen in the most recent survey. Students should then use resources on the Web to find out more about each worm's habitat. They should prepare a presentation explaining the data they found and what is each worm's most common habitat and niche. They should also consider if the native and non-native worms they research would be in competition for resources or if they could co-exist.
(Note: Throughout our discussion, we determined that with the current database it was difficult to determine if there was a problem with invasive earthworms. If the current distribution of worms were compared with the historic distribution of worms, then sample areas where further study could occur could be determined. Students also concluded that unless something was seen above ground it would have been very difficult to conclude anything "bad" was happening. They concluded that this was an area where further study was important since rich topsoil was necessary for many of their families' livelihoods.)
Students should share their presentation with their classmates. While presentations are occurring, the rest of the class should take notes over each presentation using the following graphic organizer. (Note: students should complete a graphic organizer for each presentation including their own.)
Once presentations are complete, students should be separated into groups of two. They should create an public education plan to inform people the effects of non-native earthworms to the prairie. They should brainstorm a plan to help manage the spread of non-native earthworms.
After they have developed a plan, one student should rotate around the room and learn more about other groups' plans. One person should remain at the desk and present to the rotating teams. The rotator should gives constructive feedback about each team's public education plan.
Student groups should then come back together and draw an educational poster that explain their plan.