Annual reproductive cycles were studied of 12 species of crabs from different habitats of the south-west coast of India on the basis of the incidence of ovigerous females in monthly samples. The swimming crabs such as Scylla serrata, Portunus sanguinolentus, Charybdis cruciata and Charybdis hoplites pusilla show a tendency to breed continuously with distinct periods of peak reproductive activity during the annual reproductive cycle. The shore crabs such as Uca annulipes, Uca marionis nitidus, Sesarma quadrata, Ilyoplaxgangetica Metopograpsus messor and the bottom species such as Matula lunaris and Dorippe astuta and the swimming crab Portunus pelagicus do not breed all round the year though their breeding season, periods of intensive activity can be noticed.

The shore crabs of this area apparently start breeding and attain peak activity earlier than the swimming forms. Laboratory observations indicate that shore crabs do reberry during one reproductive season.

There is a steady increase in the number of eggs produced as the mature female grows and after attaining a certain size the number of eggs produced tend to remain more or less constant. The medium size groups of mature females are the active spawners among shore as well as swimming crabs.