Eddy currents being generated by external cilia of coral.  The paths of the tracer particles are colour-coded by fluid velocity. Image courtesy of MIT and the researchers

Science Snap (#32): Coral currents

Coral is misunderstood.  It may look like a beautiful underwater plant, and for a long time it was thought to be one, but is in fact an invertebrate.  The coral structures are colonies made up of individual small polyps.  These produce an exoskeleton made up of calcium carbonate, which helps to preserve them in life and also in […]