There are limits and seasons for catching female crabs.

Only female crabs, full of roe, were served.

You can distinguish male and female blue crabs by the "key" on the belly: males have the Washington Monument; females, the nation's Capitol.

The female crab drags herself up the beach with the male clamped on her back.

The female crab stirs the water with her claw to aid the flow of the water.

This is due to the fact that female crabs brood fertilised eggs on their pleopods.

The breeding season - when female crabs crawl ashore to lay their eggs - peaks during the full moon in May.

Scientists have used a robotic crab to show that female fiddler crabs prefer males who can wave off the competition.

Marshes also provide life-saving cover for female crabs that have shed their shells in preparation for mating.

The male crabs are usually twice the size of the female crabs.