When the female is ready to mate, the male will carry the female beneath him by holding her with his first pair of legs. After she sheds her shell, the male transfers the sperm to the female. She carries the sperm internally until she is ready to spawn. Sperm from this mating will live up to a year and are sufficient to fertilize all the eggs produced in a female's lifetime. After mating, the female migrates to the saltier portions of the lower bays and Gulf, while the male remains in the estuary.
Most females spawn twice and then die.
In Texas the spawning season lasts from December to October with a peak in spring and summer. When the female is ready to spawn, she fertilizes the eggs and places them on the hairs of the appendages on the abdomen beneath the apron. Of the millions of eggs spawned, few survive to become adults. Larvae pass through eight stages in about two months before becoming crablike in appearance. Young crabs move toward areas of less salty water in the back bays, where they grow to maturity in about a year.