Lump crabmeat:

Lump crabmeat is a luxury, but except for a few stray bits of cartilage that might be picked out, there is no waste. A half cup serving of the rich testing morsels of the lump crab is sufficient for most recipes.
Lump crabmeat is picked from blue crab, the same crabs that become soft shell when they molt. The smaller the pieces of crab in the tin the lower the price.

Soft shell crabs:
In order for the crab to grow, the hard exoskeleton must be shed. Then it is replaced by a new soft shell that the crab grows into. The crab molts- loses its hard shell- many times a season .
In its two to three-year life span, the average crab may molt 18 to 22 times. You can tell when a crab is about to shed its shell. About two weeks before, a white line appears along the edges of the flattened sections of the paddle fins. As the time draws near, the white line changes to pink and finally to red.
While it is shelling, the crab is called a "peeler", but one to three days before losing its shell, when the line is red, the crab is called a "rank-peeler".
The shelling process takes one to three hours as the shell cracks open and the crab backs out. At such time, the crabs are highly vulnerable to marine predators and they hide out in pilings and grassy flats. After a few hours, the new shell starts to harden.
In commercial shedding operations, the crabs are held in floating pens and once they have peeled completely, crabs are measured from point to point across the back.
Crabs less than 3.5 inches are "spiders. The "mediums" are 3.5 to 4 inches; crabs 4 to 4.5 inches are "hotels"; Crabs 4.5 to 5 inches are "jumbos". Any crabs over 5.5 inches are "whales". The "spiders", "mediums", and "hotels" seem to be sweeter and more tender. Prime-quality soft shells are not missing any limbs and they are plump and fresh smelling.
Early spring, at the beginning of the season, prices are higher, as availability increases, prices drop.
How to store soft-shell crabs
If they are allowed to breathe, and kept moist and iced, soft shell crabs will live for up to three days after they have been harvested. However, not knowing how long they have been out of the water, it is best to eat them the day you buy them. They can be frozen for six to eight months.
The best way is to wrap each crab individually. Wrap each clean crab with its legs folded under its body, in a piece of plastic wrap. Put them in single layer on a cookie sheet and freeze.
When frozen solid, put each one in a plastic bag, seal, and return to the freezer.