LOW TEMPERATURE BLOCKAGE OF MOLTING IN UCA PUGNAX

Abstract

A uniform population of 387 male fiddler crabs was used to study the effect of 10 temperatures on proecdysis following bilateral eyestalk removal. As expected, proecdysis duration is strongly temperature dependent. Proecdysis initiation is also markedly temperature-sensitive, being blocked completely at 15[degree] C or below. It blocks a substantial proportion of crabs between 15 and 20[degree] C. Temperatures blocking proecdysis also block basal limb bud regeneration (a molt-independent growth process). It is hypothesized that a metabolic event common to both processes is being blocked, possibly mobilization of hepatopancreas reserves. If Uca larval proecdysis is similiarly temperature sensitive, this factor would limit U. pugnax distribution.