EYESTALK REGULATION OF MOLT AND VITELLOGENESIS INUCA PUGILATOR

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Abstract
Ovarian maturation in the crab, U. pugilator, the relationsip of molt to reproduction, and the effects of eyestalk removal at various stages of the reproductive cycle, were studied. Ovaries from intact and from eyestalkless crabs from Florida [USA] were examined at intervals during Sept.-May. Ovarian weights of intact crabs decreased from Sept. through Dec. and began to increase in Jan. The increase was not uniform in the population and by March all stages of maturation were present. First oviposition occurred in April when about 30% of the population became ovigerous at which time about 40% of the non-ovigers had immature ovaries. Oviposition had ceased by mid-Sept. Crabs that oviposited in April showed no ovarian maturation prior to a molt in late May. A high frequency of molt occurred in Nov. and Dec. coinciding with minimal ovarian development. Eyestalk removal led to initiation of vitellogenesis in immature ovaries at all times tested and appeared to increase the rate of vitellogenesis in progress. Induction of molt by eyestalk removal was maximal in Sept. and minimal in Nov., Dec. and (for post-ovigers) in May. The basic pattern of reproduction for this species probably consists of vitellogenesis-oviposition-incubation-molt. During the reproductive season the sequence may be repeated several times. Graphic differences in length of season may depend on the number of repetitions and on the degree of synchrony within a given population.