Life-cycle of the Pea Crab, Pinnotheres vicajii Chhapgar, infesting the clam, Paphia malabarica

Various crab stages commencing with the invasive stage to adult stages of male and female in the lile cycle of Pinnotheres vicajii infesting the edible clam, Paphia malabarica, occurring in the Mandovi estuary of Goa have been described. Except the adult male and female the rest of the stages have been described here for the first time in this species. Zoeae larvae liberated from the eggs carried by ovigerous females are characterized by the presence of 3 spines on the carapace. Comparison of these larvae with those of other species has been attempted. Planktonic zoea larvae in the estuary occur almost throughout the year with 2 peak periods in MayJune and December-January, coinciding with high salinity conditions of waters. Egg counts of 12 ovigerous females of different sizes show a minimum of 611 and a maximum of 3800 with an average of 1853 eggs. An attempt has been made to study the host-symbiont relationship. No signflcant damage has been noticed on the soft parts of the host and there is no marked difference in the meat weight - whole weight relationships of the infested and non-infested clams. However, a slight decrease has been noticed in the averages of meat weights of infested clams in the bigger whole weight groups