Summary: Students use role-play to mimic the behavior of an invasive fish called Eurasian ruffe (pronounced rough) to experience firsthand how and why the species has multiplied so rapidly in some Great Lakes areas.
- 60 minutes
- 10 chairs. Place chairs in two rows of five, back to back.
- Nautical or fish music.
- CD player
- Set of Ruffe Musical Chairs Game Cards. Print ruffe cards on card stock, and cut out individual cards.
Part 1 – Preliminary Discussion
- Introduce or revisit the basic needs of animals. Students need to understand that all animals must meet have their needs met for food, water and habitat in order to survive.
- Ask volunteers to describe times when they looked for something they wanted or needed and it wasn’t there, or when they went to do something but there wasn’t room for them to participate. After hearing a few of these stories, ask the students what it felt like. Ask them to imagine what it would be like to not meet a basic need like food, water or shelter.
- Ask students if they think that there are instances in nature when animals can’t meet their basic needs. When might this happen? Explain that students will experience this during the game they are about to play.
Part 2 – Play the Game
The first half of the game demonstrates the competition for food and habitat.
- Start with two rows of five chairs, placed back to back in an area clear of other furniture. Explain that the chairs represent the basic needs of native fish in the Great Lakes — meaning they represent food, water and shelter. Choose five students to represent native Great Lakes fish and play the game just like “Musical Chairs.” Because there are five students and ten chairs they will easily find seats.
- Explain that since they were so easily able to meet their needs, they were also able to produce offspring. Add five more students and play again. All seats will now be full.
- Add five more students (15 total), due to reproduction, and play again. This time, when the music stops, there will be plenty of competition to observe. Those students who can’t find seats get eliminated. Ask or explain what this represents.
- Answer: When too many creatures are produced, those who can’t find food or meet other needs must leave the area to look elsewhere or die.
- Play a few more rounds with 15 students until all students have had a chance to play.
- Place ruffe cards face down on three of the seats. Play the round with 15 students again, and have those who land on cards read and interpret them. Explain that ruffe are a new kind of fish accidentally introduced into the area by ocean-going ships. Ruffe are competing for the same needs as the local or native fish. If students have a card with “Sorry, you lost your seat,” they are eliminated for that round as well as the students who couldn’t find a seat.
- Pick up the ruffe cards, shuffle them with the others and put six down on different chairs. Play the round with 12 students instead of 15 (because with less food, water and habitat, there will be less reproduction and survival of young). Again, those cards with “Sorry, you lost your seat” are eliminated along with those who don’t find chairs.
- Pick up the cards, shuffle, and put down eight cards. Play the round with eight students.
- Cover all the chairs with a card, shuffling between rounds, and play until no student (representing Great Lakes fish) survives the round.
Part 3 – Discuss the Results
- Ask students what it feels like to have the ruffe taking over their lake. Ask if they know of other species (plants or animals) that try to come in and take over where they don’t belong.
- Dandelions and other weeds are good examples.
- Explain or have the students explain, that non-native species like this can create real problems for the native species living in an area because they compete for basic needs.
Part 4 – Modify the Game
The second half of the game demonstrates what happens when predators are also considered.
- Play the game again with 9 native fish, 2 predators (representing walleye and northern pike) and 2 ruffe.
- If the “predators” don’t find seats when the music stops, they’re allowed to eliminate other “fish,” or take over chairs. (Predators prey upon smaller fish.)
- Play the game until the ruffe finds a seat. For every successful ruffe, add 2 more ruffe, and continue playing the game. (The ruffe population has established itself and is growing rapidly.) The predators are not allowed to eliminate ruffe, or take over their chairs, because they prefer feeding on native species. (Ruffe have spiny fins that are hard to digest.)
- Keep playing until the ruffe have taken over most or all of the seats.
Part 5 – Discuss the Results
- Ask the students why ruffe were so successful in taking over the chairs. Explain that all these things are true for ruffe in the Great Lakes and they are expanding at a fast rate and into new areas.
- Ask the students if they know of any ways to prevent the spread of ruffe. Indicate the things mentioned in the background material if the students don’t think of them.
Adapted from Musical Mussels. From Fish Ways Project, MNR, Ontario, Canada.
Additional details and photos about aquatic invasive species, see: www.miseagrant.umich.edu/ais