Whirled Peas: A Case Study in Legume Buoyancy

I make a lot of salads, more in summer months, but probably at least 50 per year. I also have been known to, on occasion, blogaboutsalads. One of our favorite salad ingredients is peas. We buy them frozen in a bag, pour a few into a glass, and add warm water to thaw them. One of the things that puzzles and fascinates me every time I thaw peas is that 20% of them float. And it's roughly the same percentage every time. Why would this be? Do the sinking peas have a skin breach that is letting in water? Do the floating peas contain air, or is it some property of the cell tissue? Is the freezing and thawing process relevant to this phenomenon? Do fresh peas float? Naturally I made a video to demonstrate this phenomenon. The stirring allows the floaters and the sinkers to segregate.

You can see why I don't get much sleep at night.