On the California coast, in May and June the season is at its height.
Females carry their eggs for a period of four to five months.
It appears that in general, mating of the California forms takes place in the late spring or early summer, although females with eggs are found throughout the year. Animals may be kept in large fingerbowls which are three-fourths filled with sand. An abundant supply of running sea water, led in under the sand, should be provided. Embryos may be removed from the egg-mass at any time, by holding the female gently, prying up the telson, and removing a few embryos with forceps. The eggs are orange to scarlet in color, and measure approximately 380 microns in diameter.