Book 24, Question 29 · Video
Why do some cicadas spend 13 or 17 years underground?
Periodical cicada nymphs live in the soil, feeding on sap from tree roots, for either 13 or 17 years. Then, all in the same year, they climb out, shed their skins, and become noisy adults. Emerging in huge numbers means predators can't eat them all. Scientists think prime numbers like 13 and 17 helped them avoid being on the same schedule as predators.
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What Crafty Clover says in this video
Intro
Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why do some cicadas spend 13 or 17 years underground?
The Big Idea
Some cicadas spend 13 or 17 years underground! Then they all come out at once. Why such a long, strange wait?
Nymphs Underground
Step one: Nymphs Underground. Periodical cicada nymphs live in the soil for either 13 or 17 years. They feed on sap from tree roots.
All at Once
Step two: All at Once. Then, all in the same year, they climb out, shed their skins, and become noisy adults. Coming out in huge numbers means predators cannot eat them all.
Prime Numbers
Step three: Prime Numbers. Thirteen and 17 are prime numbers. Scientists think these odd schedules help cicadas avoid lining up with their predators' cycles.
A Closer Look
Let's take a closer look! The nymph waits underground. It climbs out of the soil. It sheds its skin. It becomes a noisy adult.
Quick Facts
Quick facts! After they emerge, adult cicadas live only a few weeks. Male cicadas make a loud buzzing song. Their empty skins are often left clinging to tree bark. Cicadas do not bite or sting people.
Think Like a Scientist
Now, think like a scientist! If a group of cicadas came out in 2021, with a 17 year cycle, when will they come out again? Add 17 to 2021. Write down your answer. Then try a 13 year cycle too. Check your math with a grown-up.
Outro
Periodical cicadas spend 13 or 17 years underground sipping root sap, then emerge all at once in huge numbers so predators cannot eat them all. Science is amazing! The world under your feet is full of surprises. Keep digging into big questions, and keep exploring with me! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!