The MMS Blog

Two Lessons in One: Studying “Sewer Lice” and Learning More than We Bargained For

Our science teacher Dr. Koh has often pushed us to question our observations. In many demonstrations, she has used everyday materials to show us that things are not always as they appear.  I am going to talk about one particular demonstration where she showed us live “sewer lice.”

Our lesson started with a question: “How do living and nonliving things operate to meet the needs in an ecosystem?” We started off discussing “How do we know if something is living?” Responses ranged from: “it needs to have cells,” to “it needs food to survive,” to “it needs to reproduce.” Dr. Koh then told us that we could observe the relationship between living and nonliving things with some samples of sewer lice, sent to her by a friend, named Professor Burkhard. These sewer lice had evolved from human head lice and adapted to swim in the sewer, only swimming up to the surface to breathe. She brought out three samples in total of the sewer lice: a one-week-old sample, a two-week-old sample, and a six-week-old sample.

The first sample (the one-week sample) had brown water which resembled sewer water, and the sewer lice were smaller. The second (the two-week sample) was slightly clearer with larger lice, and the third one was completely clear with the biggest lice. We concluded that the sewer lice and their environment play a mutually beneficial relationship: the longer they were in the water, the more the sewer lice grew—and the clearer and purer the water became. This shows that living and nonliving things can work together. This outcome can actually help with two of the biggest problems facing humans: hunger and pollution.

But, then the demonstration taught us another lesson! Dr. Koh unscrewed the lid of the last jar and took out one of the lice–and ate it! She explained to us that “sewer lice” do not exist and that they were just raisins in a mixture of varying amounts of coffee and seltzer water. This was actually a fake simulation. Dr. Koh had just made up the story to hook us and make us focus on the original question: “How do living and nonliving things operate to meet the needs in an ecosystem?”

After this demo, I realized that you can’t just accept many things in life without questioning. You need to ask questions and not believe in something until you have reason to believe in it. I learned that questioning things is a good way to see the truth behind a scheme.

-Joseph K.

Posted on October 23, 2018 in