The blue-claw crab is also known as Callinectes sapidus. Female Blue-Claw Crabs mate only once in their lives when they become mature enough. When they are close to their pubertal molt they release a pheromone in their urine that attract the males. The male crabs will fight for the females and carry them around until molting occurs. The two will mate when a female’s shell is soft. The females store the male’s sperm in sac-like receptacles. The male will leave her once their shells have hardened. The females will move to waters of higher salinity to spawn.
This picture shows two Blue-Claw Crabs mating.