PPS is a severe and potentially deadly affliction crabs get from being moved from their home on the beach, to a store, and finally to your home.
Imagine if you will, that you are a PP living on a relaxing stretch of beach in the Virgin Islands. You spend your day snoozing on the warm toasty sand and the night ambling about under the stars for food and water. Its a life we all dream about, right? Well it doesn't last forever. Soon a man comes along picking you and your crabbie friends up and puts you in a small cramped box with dozens of other crabs. You are then jostled about as you are shipped to the States and if you are lucky you go straight to an awaiting pet store. If you are unfortunate, they take you to a place where they employ ghastly methods to get you into hideously painted shells that not only look bad but fit poorly. Then they ship you to the store along with the lucky crabs that haven't been forced into painted shells. At the store, they put you in a relatively small tank, which is over crowded, and where humidity is low and the heat is room temperature or lower. If you haven't been stressed out yet then you have a costumers tapping at the glass and kids shrieking in delight as they stare at you through the glass. Your ordeal is yet to be over with. You are then purchased by a costumer and taken to a home to live out the remainder of your life behind glass or plastic as the case may be.
Its no wonder that many crabs die from PPS. You can prevent this as best you can by placing your new crabs in a nice dark quiet tank with deep substrate and plenty of hiding places and try to have as little contact with the crab for the first three or four weeks as possible. It must be said, however, that despite our best efforts, that some crabs, especially the bigger ones, are just to far gone from PPS to save. If that is the case with your crab you have my deepest sympathy and condolences.