This allows them to scoop up or scrap algae off of the bottom or rocks. Those with a diet of shellfish have heavy claws with blunt teeth. This allows them to catch their prey and crack their shells. The crabs that are scavengers have shape pincers, which allows them to tear apart their food. The filer feeders have claws which and scoop up mud and other bottom materials.
Crabs appear to go through an extensive courtship behavior before mating.
Pheromones are important in sexual attraction. 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.