Michael Weber from the MPI-CBG group of Jan Huisken came in 2nd in the NIKON 2013 Small World In Motion Competition with his video of a beating heart of a two-day old zebrafish embryo. The heart is only 250 micrometers (just a bit more than the diameter of a human hair) and was reconstructed in 3D after being captured using light sheet fluorescence microscopy in the living zebrafish. In one of its more mesmerizing facets, viewers can watch the movement of blood cells through the heart and its adjacent vessels.
VIDEO of the beating zebrafish heart.