Powerful jaws feature so prominently in science articles and documentaries that descriptors such as “bone-crunching” or “lightning-fast” hardly mean anything anymore. We’re all familiar by now with the animal kingdom’s impressive array of armaments, and jaws are some of the most widely-used tools for catching prey and defending oneself.
Among the diverse cast of characters with menacing mouthparts, trap-jaw ants (Odontomachus sp.), although tiny, are awe-inspiring in their own right. With jaws that open a full 180 degrees and span a distance significantly wider than their heads, the ants can strike at the breathtaking speed of 225 kilometers (140 miles) per hour and with a force 300 times the insects’ own weight. In addition to the more conventional functions that jaws perform in other animals, trap-jaw ants employ theirs in a truly novel way: locomotion.
"Lens of Time: Jaw Jumpers" was first published on bioGraphic © 2019 California Academy of Science.
Video produced by Spine Films
Sheila Patek: Trap-jaw ant's are ants that use their jaws for capturing prey, for fighting other ants, launching themselves in the
air literally jumping with their jaws.
Jumping with jaws is not a normal thing in biology, that is for sure. I can't think of anything else that jumps with their jaws.
The ants have to store up energy in their head or some other elastic structure, and then release this energy when they release the latch and the jaws slam closed.
Trap-jaw ants produce the highest acceleration ever recorded in an animal of that size. Trap-jaw ants are accelerating their jaws an order of magnitude more than a bullet in a gun.
I work right at the interface of physics and evolution in a field called biomechanics. A large focus of my labs research right now is on systems that use power amplification, which means that they're performing the motions with springs and using latches to generate very powerful movement.
We've filmed trap-jaw ants at over a hundred thousand frames per second.
In regular daily time the ant is on the ground and then you can't find it. But when you put a high-speed video on it what came out was this ant slowly positioning its head against the ground. And the next thing you know there's an ant slowly spinning through the air and the most improbable parabola of motion.
At one level I can tell you how they're able to do it. On another level I can say we don't really understand yet.
Zeynep Temel is a mechanical engineer. She works on engineering fabrication and principles and pushing the limits often with an eye towards biology.
Zeynep Temel: We have been working together for a little bit more than two years. The ultimate goal is to understand the behavior of the trap-jaw ants better, but as an engineer what I'm interested in is if I can use this motion in potential applications.
Microrobots come across a lot of obstacles during their motion so jumping is a very good way to overcome the
obstacles especially when they are stuck.
At the moment we have a prototype inspired by the trap-jaw ants. And when I first started designing the synthetic ant head I used both CT scans and video images from Patek lab.
In order to manufacture robots that small we cannot use groups we cannot use not screws, we cannot use nuts, bolts...they're all out of questions because they are all very big for the scale of our robots.
In order to solve that problem we use origami inspired folding techniques to manufacture our robots. You have to be patient and you have to have steel hands in order to assemble it.
In my mechanism I have two mandibles that sit on the latch. When I start applying heat the mandibles start rotate and applying a force on the latch and the latch can only hold mandibles up to a certain point.
Patek: That little thing right there is a latch?
Temel: Yeah, there.
Patek: That is crazy.
Temel: It is very tiny. It's a little bit difficult to put it in.
Patek: When Zeynep came in and was looking at the trap-jaw ant morphology she pointed out things that didn't make sense to her that we hadn't even thought about his biologists.
Zeynep worked a really long time to build a physical model that matched what the literature says about how the latch works in ants and she couldn't do it. It just didn't work right. So she went and used a different latch in her model.
We're realizing that maybe we've actually misunderstood it all this time and in fact the latch and trap-jaw ants probably works a lot more like the one that she realized would work in this case.
One of our basic questions is is this an efficient way to jump?
We're working very hard on trying to figure out how elastic energy is stored in the head and released.
Zeynep's model provides a phenomenal way of looking at that energy delivery to the system.
We were so focused on the jaws closing and filming that extraordinary movement that we never thought to look at the head. We started to realize there had to be a spring somewhere.
We just had kind of had to shift where we were filming and slow down the frame rate. All of a sudden this crazy motion showed up.
The entire sides of the head of the ant squash in.
We basically blow on the ant or do something to stimulate it to load its jaws and then you'll see the head just start to flex.
Besides bowing in the whole head like getting shorter as it's flexing and then we can measure that motion and
measure the shape changes and start to learn about three-dimensional springs.
We don't normally think of a three-dimensional geometry being used to store elastic energy.
Yeah you can really see how she compressed the sides of her head in are all squeezed in and the top of her head...
The trap-jaw ants are giving us insights into a more diverse set of design principles for storing elastic energy.
What I feel is unique about this collaboration is how close we work together. It's a very rich and tight connection between biology and engineering.
Temel: There are things that we cannot do with real animals. We cannot actually cut the mandibles off the trap-jaw ants and so that they have shorter mandibles and see what happens.
But we can do this with our robots and we can learn trap-jaw ants have the mandibles at that size or at that shape or how much energy we need in order to perform a specific jump height for example.
Patek: So these are the things that we can learn by studying our bio-inspired mechanisms.
There is a broader piece of this, which is the joy and value of knowledge.
This kind of work is literally about technology yes but it's also about the joy of being a biological system ourselves.
Of understanding the planet we live on.
There there is such value in just that.