FOOD-INDUCED SIZE-SPECIFIC MOLT SYNCHRONY OF THE SAND CRAB, EMERITA ANALOGA (STIMPSON)

¹ Department of Biological Sciences, University of California, Santa Barbara, California 93106

Synchronous molting was found in both laboratory and field populations of the intertidal, filter feeding anomuran Emerita analoga. Molt synchrony resulted in distinct peak and trough molting periods which were apparently independent of lunar phase and not pheromonally entrained. The intermolt period for Emerita was correlated with animal size.

Laboratory experiments showed that the molt cycles of a previously synchronized group of female Emerita analoga could be desynchronized and resynchronized by altering feeding regimes.

It is proposed that in nature the increase in phytoplankton, which characterizes the spring bloom, entrains the synchronous molting rhythm observed in the field.

Synchrony tends to be obscured in field samples composed of broad size ranges because of the size-specific character of the intermolt period. For animals which molt synchronously, estimates of growth rate based on molt frequency data extrapolated from field samples can be variable and misleading.