Low Temperature Blockage of Molting in Uca Pugnax

A uniform population of male Uca pugnax was used in studying the effect of 10 temperatures on proecdysis resulting from eyestalk removal.2. Proecdysis duration is shortest at 29° to 32° C. and lengthens significantly at lower temperatures.3. Proecdysis initiation is markedly temperature-sensitive. At 15° or below initiation is completely blocked; at 15° to 20° a substantial proportion of the crabs fail to begin proecdysis.4. Temperatures which block proecdysis initiation 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.5. The physiological and ecological significance of the proecdysis temperature block is considered.