Influence of light on endocrine system and ovarian activity in the ocypodid crabs Ocypoda platytarsis and O. macrocera

Abstract

Although photic stimulation represents an important extrinsic factor controlling re produc-tJon m manne mvertebrates, pertine nt information 1s scanty for marine crustaceans. We investigated light-induced biochemical changes in ovary, he patopancreas, muscle and haemolymph of the ocypod1d crabs Ocypoda platytars1s and 0. macrocera in order to determine metabolic changes during ovarian maturauon under altered light intensities. Increased light inte nsity caused acceleration of oocyte maturation in 0. macrocera but no appreciable change m oogenetic activity of 0. platytarsis; however, there was a sudden rise in metabolic activity of ovary, he patopancreas and muscles in both crabs. Cytological observations mdicated hypertrophy of cormectJve tissue and follicle cells in the ovary of 0. platytarsis. In both crabs eyestalk neurosecretory cells (NSC) showed more secretory activity under e levated light intensity. A corresponding increase in secretory activity of the NSC of brain and thoracic ganglion was evident solely in 0. macrocera. Increased secretory activity of NSCs in brain and thoracic ganglion of 0. macrocera is suggested to be responsible for the acceleration in oocyte maturation. The differences in the reproductive response to photic stimulus of the 2 crabs may be related to their different breeding habits.