Fig. 5. Details of the relative timing of tracheal compressions and CO₂ pulses in different regions of the body of Pterostichus stygicus. Gray banding represents the total duration of the compression cycle (from collapse to reinflation), identified from movie records. The green lines indicate the start of compression, with line thickness representing the duration of tracheal collapse phase. The boxes above each trace indicate which part of the beetle was in (x-ray) view during CO₂ recording; arrows represent translation of the beetle to a different body region. Data are from one specimen (mass 130.0 mg).