In tropical species courting appears to take place in daylight hours and reaches a peak at the time of low tide. Males may attract females by waving their claws. The male entices the female to his burrow by rapping at the opening. Once the female enters the burrow matting is completed. In many species the female remains in the burrow to lay the eggs.
Crabs are a necessary part of the estuary system.
Their scavenging tendencies help to keep the estuary form becoming polluted. They are an important part of the food chain. It is because of the crabs that the estuary system is able to maintain is balance.