Sentence:  Once the crab has molted, the new shell takes about four days to harden. Just after shedding, the blue crab's shell is soft enough to eat. Watermen harvest soft shell crabs as <WSD>peelers</WSD> (about to shed), rank <WSD>peelers</WSD> (within hours of shedding)  and busters (in the process of shedding). 
Meaning of the word marked with <WSD> tags:  An edible crab that is about to shed its shell.