Fig. 1. Diagram of open-flow respirometry setup used in measuring respiratory evaporative water loss (REWL). Components are not drawn to scale. The fiberglass board (A) used in the experiment was fitted with sloping side-boards and carrying handles, which have been omitted from the diagram for the sake of simplicity. The other components were: B, PVC collar; C, Teflon funnel; D, 1 m-long Teflon tube; E, Singer dry gas meter; F, vacuum pump; G, a sample line which carried a fraction of the incurrent air to a relative humidity analyzer (H); I, oxygen sensor; J, air flow controller for sample line; K, analog-to-digital data converter; and L, computer used to record output. Solid lines (between H,I,K,L) represent data cables. For further details see Materials and methods.