Two major difficulties are encountered when dissecting a herring in order to examine its respiratory functions. The first resides in the nature of respiration, which is complex and hard to show because it is so rapid. The second stems from the properties of oxygen, which is invisible in water.

How does one illustrate the decomposition of respiratory movements in a herring without distorting reality? Because it is complex, stealthy and above all invisible, the path of oxygen from the mouth → gills → operculum was illustrated by small bubbles. To make the understanding of this process even clearer, 3Dmedicus represented the gills as “hairs” whereas a system of pre-defined, color-coded cross sections highlights the group of organs.