Soft-shell crab, sometimes abbreviated to just soft-shell, is a seafood delicacy with the entire crustacean capable of being eaten, a result of catching and cooking crabs shortly after they molt their hard shell. The Chesapeake Bay, shared by Maryland and Virginia, is famous for its soft-shell blue crabs.
While all crabs shed their shells to grow, only a few species of crab can actually be eaten in this form. The Blue Crab is the primary commercially available soft-shell product. The scientific name, (Callinectes sapidus), is derived from Latin and Greek. Calli = beautiful; Nectes = swimmer; sapidus = savory. The translation is not only accurate but surprisingly poetic - the beautiful, savory swimmer. Blue crabs grow rather rapidly, 12 - 18 months, from the juvenile stage to adulthood. A full-grown Blue Crab will measure nearly 8 inches across.
The exact species used as soft-shells varies from region to region. In the United States, the blue crab is used typically, although the use of the mangrove crab in Asia has provided another source for this seasonal food. As these crabs grow larger, their shells cannot expand, so they molt the exteriors and have a soft covering for a matter of days when they are vulnerable and considered usable. Fishermen often put crabs beginning to molt aside, until the molting process is complete in order to send them to market as soft-shells.
With the blue crab in cold waters this molting is highly seasonal and usually lasts from early May to July. Demand for this delicacy has increased with the use in Japanese and other cuisines, so that the mangrove crab has been used as an alternative source from Asia. Because mangrove crabs grow in tropical muddy flats all year round, such swamps provide a continual source of soft-shell crabs. In warmer waters such as the Gulf of Mexico, soft-shell crabs are available for longer periods. The crabs continue to molt throughout the year, but in smaller numbers, sometimes making it unprofitable to fishermen to maintain traps through those periods.
If a waterman catches a crab nearing the end of its molting cycle (rank peeler or red sign), he will place it in a special holding pin where it remains until it molts. Serious soft-crabbers will build tanks up on a pier or on the shore… These shedding tanks may be either open system (circulating sea water) or closed system (like a fish aquarium).
Immediately following molt, the crab’s shell begins to ossify, or harden. It is crucial that the crab be removed from the water as soon as possible to help stop this process. Usually soft-shell crabs must be eaten within four days of molting to be useful as soft-shell crabs. They begin to rebuild their shells after that, and when eaten, have a thin shell developing. They are referred to as “papershells” and are more crunchy when eaten, making them less desirable to many people. Because of this, the floats (or tanks) must be checked routinely every three or four hours, 24 hours a day, seven days a week!
Culinary: When possible crabs should be kept alive until immediately before cooking… Dressed or whole freshly dead soft-shell crabs have a shelf life of 4–5 days with proper refrigeration… This may actually be the optimal way to prevent further ossification (hardening) of the shell. To check freshness of a whole dead soft-shell crab… simply pull back the top corner of the shell and smell the gills for freshness.
Soft-shells are split up into 5 basic sizes; whales, jumbos, primes, hotels and mediums. A sizing and weight chart is provided as follows;
Whales: over 5 ½ inches; 5.9 oz avg wt; 2 dz per tray; 6 dz per cs
Jumbos: 5 - 5 ½ inches; 4.5 oz avg wt; 3 dz per tray; 9 dz per cs
Primes: 4 ½ - 5 inches; 3.3 oz avg wt; 4 dz per tray; 12 dz per cs
Hotels: 4 - 4 ½ inches; 2.5 oz avg wt; 5 dz per tray; 15 dz per cs
Mediums: 3 ½ - 4 inches; 1.8 oz avg wt; 6 dz per tray;; 18 dz per cs