The researchers, in a team comprised of materials scientists and biologists, first attempted to describe the fluid acquisition mechanism of butterflies. Believe it or not, this has been a hotly debated topic in entomology. A typically used model is the "drinking straw model", which is flawed because it requires us to assume that the proboscis is a straight tube, which it is not. To test the validity of this model, the authors looked at the permeability and flow of the drinking region of the proboscis.
There's a lot of math in this paper, some of which was later corrected, but the gist of this paper is: according to the math, butterflies and moths shouldn't be able to drink from their proboscis. Because of its shape and structure, the pressure differential required for the suction to work is greater than 1 atm. For context, no vacuum pump can produce a pressure differential greater than 1 atm on Earth. The authors suggest that the insects use a behavioural strategy to overcome this problem, by altering the taper, length, pore size, and placement of the proboscis, and how they use it, ultimately making it act like both a sponge and a straw.
|Monarch butterfly proboscis under |
a scanning electron microscope
What is especially exciting about this research is the awesome example of what happens when scientists get out of their silos and start collaborating across disciplines. This study was the result of collaboration between biologists and engineers, to look at the same problem from different perspectives and come up with a meaningful solution.