Schematic presentation of experimental tanks (lateral view) for the three group sizes. Note equal surface areas (S) per individual (in cm2) within group sizes. Dashed horizontal lines indicate the water level. Vertical panes are indicated by vertical lines. Note that water volume per individual was kept constant at 612 ml by placing each experimental tank into a larger standardized water tank (not shown).
Sprenger et al. BMC Evolutionary Biology 2011 11:107 doi:10.1186/1471-2148-11-107