You can drive a car over the iron beetle and it will survive. Shocking, huh? But the culprit is the microstructures of this insect, the beetle's armor, making it almost impossible to crush.
The iron beetle is like a tiny tank. Its sturdy exoskeleton doesn't let supposed predators chew it up. But analyses of microscope images, 3D printed models and computer simulations of the beetle's armor have revealed some of its secrets. Researchers report in Nature on its tightly interconnected, impact-absorbing structures. The structures connect parts of thethe beetle's exoskeleton and help it survive enormous crushing forces.
These features can inspire new, more robust designs for body armor, buildings, bridges, and vehicles.
The 'unbreakable' iron beetle
This iron beetle has a really hard to crush shape and lives in the desert regions of western North America.
David Kisailus, a materials scientist at the University of California (Irvine), reports that it is less rounded than the Namibian beetle, low on the ground and flat on top. In compression experiments, Kisailus and colleagues found that this beetle can support about 39,000 times its own body weight.
In other words, that would be equivalent to one person carrying a stack of about 40 M1 Abrams battle tanks.
This slice of an evil iron beetle's back shows the jigsaw-like links that connect the left and right sides of its exoskeleton. These protrusions are tightly interlocked and highly resistant to damage, helping to give the beetle its incredible durability.(DAVID KISAILUS)
Within the iron beetle, there are two important microscopic features that help it resist everything and everyone and not get crushed:
- The first characteristic is the series of connections between the upper and lower halves of the exoskeleton. They are like two halves of a shell positioned one on top of the other, so they fit together.
But these striated connections take different shapes on the beetle's body. So near the front of the beetle, around its vital organs, the ridges are highly interconnected, rigid, and resist bending under pressure. At the back, on the other hand, the connective ridges are not so interconnected, allowing the upper and lower halves of the exoskeleton to slide slightly past each other.
It is this flexibility that helps the beetle absorb compression into a region of the body that is safer to crush;
A series of protrusions also, called blades, fit together like puzzle pieces to join the two sides.
These blades have layers of tissue bonded together by proteins and are very resistant to damage. So when the beetle is crushed, little cracks form in this protein glue between the layers of each blade.
It is the small curable fractures that are allowing the blades to absorb impacts, without breaking completely. explains Jesus Rivera, engineer at UC Irvine.
The revelation of the biological architecture that makes the iron-coated exoskeletons of beetles nearly impassable could help engineers design more impact-resistant structures.
The scientific study was published in the journal Nature.