Invisible Nature: Code of the Treehopper

Grade level: 6-13+
Length: 5 minutes
Next Generation Science Standards: PS4.A, LS4.C

Summary

Treehoppers, pea-sized insects of the family Membracidae, communicate with each other in an intriguing way: using jiggles. By rapidly bouncing their abdomens, they send vibrations down through their legs and into the plant they are standing on. Nearby treehoppers pick up and interpret the vibrations, which vary in frequency and pattern depending on the message being conveyed. Now, scientists are listening in, and starting to crack the treehopper code. And it turns out, the conversations are happening nearly everywhere they eavesdrop—from tropical rainforests to urban gardens. Your own backyard may in fact be hosting a cacophony of communication that is imperceptible, until you listen in just the right way.

Video Discussion Questions

1. How do treehoppers communicate with one another?
2. How do we know that treehoppers communicate with each other even though we can't hear them?
3. How do male treehoppers use their communication style to compete with each other over a female?
4. How common is the communication style of treehoppers in the insect world?

How can one treehopper feel the vibrations another nearby treehopper is making with its abdomen? 

To answer this question, we need to dive into the physics of mechanical waves.  In this activity, students will explore how energy can be transmitted by waves through a medium using an online PhET simulation.  They will then use what they learned from the simulation to make a hypothesis about how treehoppers can communicate via vibrations.

Materials

• Computers with the PhET Wave on a String interactive simulation

1. Show your students the Code of the Treehopper video and discuss it as a class using the Discussion Questions above.

2. Have students write in their science notebooks how they think treehoppers are able to send messages to one another via vibrations.  What could be going on physically?

3. Individually or in pairs, give students about 15 minutes to play with the simulation.

• In their science notebooks, students should write down observations about the behavior of the string in the simulation and how it changes when the parameters (damping, tension, etc.) change.

4. Bring students back together as a class and discuss what they observed in the simulation.

Image credit: Tess Watson

Perhaps you've seen a sci-fi movie or TV show that features epic battle scenes in outer space replete with the sounds of lasers and explosions. However, sound doesn't travel through a vacuum, so in reality such scenes would be anticlimactic in their silence.

Activity premise: You are an astronaut on the International Space Station. You and a fellow astronaut are outside of the station (in proper space suits) doing a spacewalk when the microphone in your helmet that you use to communicate with the other astronaut stops working. The two of you are connected by a rope to each other and to the space station.

Annette Heist is a science writer, radio producer, and a registered nurse working in behavioral health. Ruth Lichtman is a multi-disciplinary visual artist and filmmaker whose work has been featured on The New York Times, The Atlantic, Aeon, and The Huffington Post. Flora Lichtman is a science journalist who has worked for “Bill Nye Saves the World” on Netflix, The New York Times, and Science Friday. She hosts a podcast called Every Little Thing.

This video was produced for bioGraphic, a magazine powered by the California Academy of Sciences to showcase both the wonder of nature and the most promising approaches to sustaining life on Earth.

Good Vibrations: 7 Animals That Use Vibrations to Communicate
Did you know that termites bang their heads on the ground to alert their colony of an impending attack? Read about other animals that use vibrations to communicate in this National Geographic article.