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STANDARDS
CCSS: 7.SP.B.3, MP1, MP4, MP8
TEKS: 7.12B, 7.12C
DATA ANALYSIS
The Bugs on Us
Meet some of the tiny residents that call our bodies home
David Scharf/Science Source
A head louse (above) clings to a human hair near an egg, called a nit. Adult female lice can lay 80 to 100 eggs over their lifetimes
Don’t panic! Right now, there are thousands of tiny mites on your face. These eight-legged creatures live inside your hair follicles—pouches in the skin from which hairs grow.
You shouldn’t bother rushing to the sink to scrub them off (it wouldn’t work anyhow). Having face mites is totally normal, says biologist Megan Thoemmes of the University of California, San Diego. She worked on a project that examined the faces of more than 4,000 people for these critters, called Demodex mites.
Scimat/Science Source
Gut bacteria Lactobacillus acidophilus
“We haven’t found a single person without them,” she says. Demodex can live all over our bodies. But they’re most abundant on our faces, where they may eat dead cells and an oily substance called sebum. The mites are probably harmless and may even benefit us in some unknown way. “They’re just hanging out, like thousands of little friends who are always with you,” says Thoemmes.
Mites are just one of the many microscopic organisms that live on us. “The body is its own ecosystem that hosts thousands of species,” says Thoemmes. “It’s like a forest, with mites, fungi, and bacteria interacting and working together to form a community.”
Many of our body’s residents, like the microbes in our gut that help with digestion, keep us healthy. But our bodies sometimes pick up problematic invaders too. Unwanted parasites like head lice can drink blood from our scalps, while certain worms can infest our intestines, robbing us of nutrients. Yikes!
Shutterstock.com
COMPARING POPULATIONS
The infographic above shows the percent of each type of microbe on different body parts. You can compare the populations of each body part’s microbe distribution to draw conclusions about where certain microbes thrive. Use the “Body Bugs” infographic to draw inferences about microbe populations.Record your work and answers on our answer sheet.
A. Which body part on the chart has the smallest percent of bacteria?
B. The largest percent of fungi?
Which body part has the highest percent of viruses? Why do you think that is?
Where on the human body will you find a distribution of microbes most similar to that behind the knee? Explain your reasoning.
Based on the diagram, which type of microbe do you think is most present on your skin? Explain your reasoning.