Abstract
Variations in the rate of molting and of fecal pellet production by C. antarcticus (Willem), collected from Signy Island in the maritime Antarctic, were measured over temperatures of 0-20.degree. C. Over the range 5-15.degree. C total fecal pellet production between molts was similar; at 0.degree. C there was little feeding activity; mortality was high at 20.degree. C. The temperature of maximum molting frequency is lower for this species than for temperature Isotomidae, suggesting cold adaptation of its molting behavior. Growth of individual specimens at 10.degree. C was measured from mandibles recovered from shed exuviae after each molt, using a linear relationship between body length and mandible length. At a body length of 1040-1134 .mu.m, individuals either increased or decreased in size at subsequent molts. The minimum age of the largest specimens of Cryptopygus on Signy Island is probably 3-7 yr.