DRYING PROCESSES IN THE ANTARCTIC COLLEMBOLAN CRYPTOPYGUS-ANTARCTICUS (WILLEM)

Live and dead specimens of the Antarctic collembolan Cryptopygus antarcticus (Willem) dry, under constant external conditions of temperature (25 or 35-degrees-C) and r.h. (0%), like most hygric soil arthropods. The drying curves of both live and dead specimens have three phases: an initial decrease; a constant rate period and a final falling rate period. The latter is exponential. Cryptopygus dries throughout these phases in a purely physical, passive manner. The constant rate period is not indicative of active metabolic or physiological regulation of water loss. The entire drying curve can be explained using drying theories developed for porous, hygroscopic solids. A similar situation pertains in the Antarctic lichen Umbilicaria antarctica Frey et Lamb. Geometrically, the percentage of water remaining at the onset of the falling rate period is related to the hydrated thickness of the collembolan cuticle or the lichen cortices. For Cryptopygus the hydrated thickness is estimated as 14-mu-m.