Flying Copepods

Wednesday 24 Jan 18


Thomas Kiørboe
DTU Aqua
+45 35 88 34 01
Some copepods, mm-sized zooplankton, that live in the very surface layer of the ocean jump out of the water and perform spectacular flights when escaping from predators. This yields them a great advantage, because their escape distance increases many fold. But how can they do it?

Many large aquatic organisms are able to break the surface tension and jump out of the water. Well known examples are, of course, jumping salmon and breaching whales. But small organisms, like mm-sized copepods, are faced with the problem of surface tension. The ‘skin’ of the water is not easy to penetrate for small organisms; that is why water striders walk so easily on the water. It has been known – but largely unappreciated - for a century that some copepods can leave their normal aqueous habitat during escape jumps, and copepods are indeed the only small organisms known to be able to do so. Previous studies have suggested that the copepods may have particular surface properties or release substances (surfactants, like soap) that enables them to do so. However, the simple answer is that their escape jumps are unusually powerful. Relative to their size, the force that a jumping copepod can produce is 10 times larger than that recorded for any other animal. Analyses of the kinematics of the flight-jumps, measurements of drag coefficients, and calculations of the necessary power to break the surface tension and overcome gravity demonstrate that it is the unusual power of copepod jumps that allows them to fly. This helps explain why these, the strongest animals in the world, are also the most numerous animals on the planet.

Read the paper here.

Svetlichny L, Larsen PS, Kiørboe T (2018) Swim and fly. Escape strategy in neustonic and planktonic copepods. J Exp Biol, doi:10.1242/jeb.167262

Figure above shows two copepods - you can see them jumping here.

26 APRIL 2018