To achieve these high speed jumps, copepods use their 4 to 5 pairs of thoracic limbs (pereiopods) which have musculature which is adapted for high force production. For normal movement, they use their feeding appendages to swim (maxillipeds). By separating these two forms of locomotion, these tiny rocket crustaceans are able to make sure their pereiopods are rested and ready to burst into action when the situation arises. Their hydrodynamic shape also assists in slicing through the water, and sometimes out of it.
Some species of copepod that reside near the water’s surface are able to use their powerful legs to propel themselves into the air to escape predation. The species Anamalocera ornata has been recorded launching out of the water and travelling a horizontal distance of up to 170mm in the air. Not only is this an impressive distance for such a small animal to traverse, the energy the copepod must expend to accelerate in its viscous liquid environment and break the surface tension of the water is proportionately higher than other animals that perform similar escape maneuvers such as flying fish. A.ornata loses 33-39% of their kinetic to breaking the surface tension while a flying fish loses less than 0.07% of its kinetic energy.
In relation to their size, copepods are 10 times stronger than what has previously been documented in other animals, the force produced per kilogram of muscle is an order of magnitude higher.
Jiang, H., Kiorboe, T., 2011. Propulsion efficiency and imposed flow fields of a copepod jump. The Journal of Experimental Biology. 214:476-486
Lenz, P.H., Hower, A.E., Hartline, D.K., 2004. Force production during pereiopod power strokes in Calanus finmarchicus. Journal of marine Systems. 49:133-144
Kiorboe, T., Andersen, A., Langlois, V.J., Jakobsen, H.H., 2010. Unsteady motion: escape jumps in planktonic copepods, their kinematics and energetics. Journal of The Royal Society Interface. 7:1591-160
Gemmel, B.J., Houshuo, J., Strickler, J.R., Buskey, E.J., 2012. Plankton reach new heights in effort to avoid predators. Proceedings of The Royal Society. 279: 2786-2792
Fox, Frank, www.mikro-foto.de, Featured Image
http://naturlink.pt/article.aspx?menuid=20&cid=53247&bl=1, Image of anamalocera ornata