Battle Butterflies
You can probably think of a lot of creatures that a military might decide to copy for its submarine designs. Sharks or giant squids. Whales, perhaps. Or what about… butterflies?
MIT reports that one of their engineers, Dr. Philip Daniel, is collaborating with the U.S. Department of Defense to a create a magnetic navigation system inspired by monarch butterflies. Daniel explains:
They’re able to migrate long distances and find the exact forest that their ancestors were born into. How? One theory is that they’re able to sense the Earth’s magnetic field. They have a compass in their head, and they can use it to get where they want to go. The question is: Can humanity take advantage of the Earth’s magnetic field to accurately navigate without GPS?
Every year, around a billion monarchs travel from across North America to gather overwinter in a few specific locations in Mexico. Because adult monarchs live less than a year, none of these butterflies have made the journey before, yet they all somehow know how to travel hundreds upon hundreds of miles to arrive in the same place. (The sheer awesomeness of this journey is well-presented in the excellent Illustra Media documentary Metamorphosis: The Beauty and Design of Butterflies (2011). If you haven’t seen it, I highly recommend it.)
Magnetic Fingerprints
Daniel calls the navigational mechanism a compass, but this is just a shorthand. The word “compass” doesn’t do justice to the equipment monarchs have, as Daniel himself would no doubt be the first to acknowledge — after all, the U.S. miliary already has compasses. But monarchs have much more. What they need to navigate from different locations across the U.S. and Canada to a specific destination in Mexico is more like a complete GPS system.
So how do they do it? Daniel explains that deposits of metal in the earth’s crust can create ripples in the magnetic field, giving certain sites specific “fingerprints” to a highly sensitive detector. It has been hypothesized that monarchs use such a system, and that’s what he is hoping to create for the U.S. military.
Monarch navigation is still poorly understood, although we have figured out some pieces of it. The hypothesis of a magnetic map is necessary because what they are already known to use wouldn’t be enough to do what they do. So far, it’s known that they have an internal solar compass calibrated with an internal clock, and an internal magnetic compass as a backup for night and cloudy weather, but both of those systems would only tell them latitudinal direction, not longitude.
A reason to suspect that a magnetic map might be the solution is that it has been shown to exist in other animals. Experiments have demonstrated that turtle hatchlings can use magnetic fields to determine both latitude and longitude, implying they possess a sort of internal geographic coordinate system based on the earth’s magnetic field.
Nobody knows how this magnetic mapping system actually works. Whether it’s turtles, monarchs, or one of the other animals with seemingly magical navigational capabilities, we can still only wonder at what they can do. But if Dr. Daniel and his lab can crack the problem and engineer even a large and clumsy human equivalent of a magnetic mapping system, it might yield clues towards the design of the natural systems. A manmade functioning version would show how the system theoretically can work, and those details might enable scientists to make hypotheses that can be experimentally tested on butterflies and other migratory animals.
As always, biologists and engineers working together yields both better manmade designs and better understanding of the designs of living creatures.
Next on the Agenda…Self-Assembling Helicopters?
Incidentally, this navigation system is not even the most impressive thing about butterfly design. Another engineering marvel, also discussed in Metamorphosis, is the metamorphosis itself. It turns out, during the transformation the caterpillar completely dissolves within the chrysalis into a gooey soup, before self-assembling into a butterfly. Needless to say, this requires an incomprehensible level of coordination and planning to succeed.
Who knows? Eventually, the U.S. miliary might invent a tank than can dissolve and reassemble itself as a helicopter.
But I guess we’d better just start where we are. For the time being, the sophistication of butterfly design is far, far beyond us.
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