The SYTOX green fluorescent dye can improve the detection of dead tardigrades.

The average fraction of living tardigrades treated with either 0, 5 or 10 mM sodium azide and scored by direct observation on brightfield illumination (colored bars, left) or SYTOX green dye linked fluorescence at 1 μM on an epifluorescence microscope (white bars, right), at either 1 h (A), 24 h (B), 48 h (C) or 6 days (D) after the beginning of the experiment. Error bars indicate the standard deviation from at least three experiment repetitions and a double asterisk represents the respective significant difference at α = 0.01 (Z-test) degree, while “NS” indicate a non-significant difference at α = 0.05 degree (Z-test). A complete description of statistical results is indicated in the text.