Dolphins glow with the flow

The dynamics of flow over the surface of animals — ranging from insects in flight to swimming fish — have been examined using optical methods and markers such as dye, air bubbles and smoke. At the same time, amateur and professional seafarers (and biologists) have considered themselves extremely lucky if they have seen the firework displays produced by dolphins swimming in waters that contain high levels of bioluminescent plankton (Fig. 1). Now, physicist Jim Rohr, biologist Michael Latz and their colleagues have ingeniously combined the two approaches, and they report their findings in the Journal of Experimental Biology1. The authors analysed the light output that is induced from natural populations of bioluminescent dinoflagellates by free-swimming dolphins, and they have used the results to interpret some of the characteristics of flow over these animals.