Lessons from a beetle’s almost unbreakable shell

Engineers hope to learn how to design stronger planes and buildings by studying a beetle that can withstand bird pecks, animal stomps and even being rolled over by a Toyota Camry car.

“This beetle is super tough,” said Purdue University civil engineer Pablo Zavattieri, who was among a group of researchers that ran over the insect with a car as part of a new study.

So, how does the seemingly indestructible* insect do it?

The species — aptly* named diabolical* ironclad beetle — owes its sturdiness to an unusual armour that is layered and pieced together like a jigsaw, according to the study published in Nature. And its design could help inspire more durable structures and vehicles.

To understand what gives the 2.5cm-long beetle its strength, researchers first tested how much squishing it could take. The species, which can be found in Southern California’s woodlands in the US, withstood compression of about 39,000 times its own weight.

For a 90kg man, that would be like surviving a 3.5-million-kilogram crush.

Other local beetle species shattered under one-third as much pressure.

A beetle surviving being run over with a Toyota Camry is like a 90kg man surviving a 3.5-million-kilogram crush. Picture: supplied

Researchers then used electron microscopes* and CT* scans to examine the beetle’s exoskeleton* and figure out what made it so strong.

As is often the case for flightless beetles, the species’ elytra — a protective case that normally sheaths wings — had strengthened and toughened over time. Up close, scientists realised this cover also benefited from special, jigsaw-like bindings and a layered architecture.

A cross-section of the shell of a diabolical ironclad beetle, where two halves of the elytra meet like puzzle pieces. Picture: Jesus Rivera, Kisailus Biomimetics and Nanostructured Materials Lab, University of California Irvine via AP

When compressed, they found the structure fractured slowly instead of snapping all at once.

“When you pull them apart,” Professor Zavattieri said, “it doesn’t break catastrophically*. It just deforms a little bit. That’s crucial for the beetle.”

It could also be useful for engineers who design aeroplanes and other vehicles and buildings with a variety of materials such as steel, plastic and plaster. Currently, engineers rely on pins, bolts, welding and glues to hold everything together. But those techniques can be prone to degrading.

In the structure of the beetle’s shell, nature offers an “interesting and elegant” alternative, Prof Zavattieri said.

Mountain bighorn sheep on Lake Minnewanka, Canadian Rockies, Alberta, Canada. The project is also studying bighorn sheep to develop impact-resistant materials. Picture: iStock

The beetle study is part of a project funded by the United States Air Force to explore how the biology of creatures such as mantis shrimp and bighorn sheep could help develop impact-resistant materials.

“We’re trying to go beyond what nature has done,” said study co-author David Kisailus, a materials scientist and engineer at the University of California, US.

The research is the latest effort to borrow from the natural world to solve human problems, said Brown University evolutionary biologist Colin Donihue, who was not involved in the study. Velcro, for example, was inspired by the hooklike structure of plant burrs. Artificial adhesives were inspired by super-clingy gecko feet.

Dr Donihue said endless other traits found in nature could offer insight: “These are adaptations that have evolved over millennia*.”

GLOSSARY

• indestructible: can’t be destroyed
• aptly: appropriately
• diabolical: bad or unpleasant
• electron microscopes: type of very powerful microscope
• CT: stands for computer tomography, a type of x-ray used for scans
• exoskeleton: hard external case instead of an internal skeleton
• catastrophically: in a way that involves great damage and destruction
• millennia: thousands of years

EXTRA READING

Big buzz about Aussie bee invention

Loud, giant insect hatches after years underground

Our insects are in big trouble

Would you eat butter made from maggots?

QUICK QUIZ

1. Why is a Camry in this story?
2. Where are these beetles found?
3. Describe what the beetle shell looks like up close.
4. What other animals are being studied to help design impact-resistant materials?
5. What is velcro inspired by?

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. Ask an Astronaut
Create a diagram that shows how and why the beetle’s shell is so strong. Don’t forget to add labels to explain the most important things in your diagram.

Time: allow 25 minutes to complete this activity
Curriculum Links: English, Science

2. Extension
In the story, biologist Colin Donihue says that the research using the beetle is the latest effort to borrow from the natural world to solve human problems.

Can you think of another insect that has something that scientists could use to help design or invent something that would be really helpful to us? For example, how could a spider’s web inspire a new invention? Write as much detail as you can. Create a design if you want!

Time: allow at least 30 minutes to complete this activity
Curriculum Links: English, Science, Design and Technologies

VCOP ACTIVITY
The Tale of the Diabolical Ironclad Beetle
Write a short story about the day in the life of the newest superhero to crawl out from under a rock … literally.

A tale of the Diabolical Ironclad Beetle (DIB) starts just like any other, but is anything but ordinary. What amazing, heroic feats with DIB get up to in your story?

Use your VCOP to enhance your writing and capture the audience’s attention.

HAVE YOUR SAY: What insect would you like to study?
No one-word answers. Use full sentences to explain your thinking. No comments will be published until approved by editors.