Host in the Shell

For Hermit crabs, suitable shells are hard to come by. So they have come up with an ingenious scheme. When a crab happens upon a shell, it scopes it out – and when it is too big, the crab sits and waits, sometimes up to eight hours. More crabs show up to check out the potential new digs, and for those whom the shell is too big, they line up and wait. And get this, they line up in size order. Up to 20 crabs, lined up biggest to smallest, waiting for just-the-right–size crab to appear. Jeff is blown away by this incredible organization, but Anthony see a problem...