Water Boatman

Image courtesy of Flickr user Sam Dredge, CC BY-NC-ND

The water boatman is an insect that spends most of its time just below the surface of ponds. It can get out of the water and fly, but is most often seen hunting for insects trapped at the water surface. This means that unlike its prey, it can pass through the surface of water without getting trapped and it can breathe both in and out of water. It can breathe underwater due to a superhydrophobic coat of tiny hairlike structures that hold the water away from its body.

Image by John Bush and Morris Flynn

In the picture here, you can clearly see the silvery sheen of the air-water interface on the dark brown body of the water boatman. This shows that the insect is never truly wet. This means it can escape the water easily. It also means that it carries its air with it underwater, so it breathes air all of the time using the same structures that land insects use. The silvery sheen does have one drawback – fish have learned that it signals lunch so they will strike anything similar!


Plastron properties of a super-hydrophobic surface N.J. Shirtcliffe, G. McHale, M.I. Newton, C.C. Perry and F.B. Pyatt, Appl. Phys. Lett. 89 (2016) art. 104106