Soft-shell crabs, often referred to affectionately as "softies," are just regular crabs (typically blue crabs) that go through a natural growth stage in the spring and summer.
When the ocean temperature starts to warm up to around 65 to 70 degrees Fahrenheit, crabs will naturally start to molt and shed their hard shells as their bodies get bigger.
For a short time after they emerge from their former shells, the outside of the crab is more like a skin, which means you can eat pretty much the entire thing.
Soft-shell crabs are only soft for two or three hours before their shells start hardening again, which historically made them very difficult to capture at just the right moment.
Softies are almost entirely edible, including the claws, legs, and bodies. To prepare a soft-shell crab for cooking, simply remove the face, lungs, and abdominal flap.