Some aspects of reproductive ecology of a mole crab Emerita asiatica Milne Edwards

Abstract

Emerita asiatica Milne Edwards is the only species of the genus inhabiting the wave-washed sandy beaches of Madras coast. The results reported in the present investigation on the gonad and egg mass indices of this crab indicate the almost continuous breeding activity of the adults in the population. The hepatic index remains low all through the year, showing no significant fluctuation correlated with the other indices. As shown by the gonad and egg mass indices, the gonadal activities in the premonsoon months are rather high and the major disruptions in these indices coincide with the southwest and northeast monsoon rains. The developmental stages of the eggs carried on the pleopods have also been determined; almost all stages have been found throughout the year, suggesting that egg development is continuous. The settlement of megalopa larvae on the beach seems, however, to be seasonal. The contrast between the near continuous breeding of the adult and the seasonal settlement of the larvae on the beach is discussed.