Movin On Up Modeling How Hermit Crabs Find New Homes

As hermit crabs grow, they regularly need to find larger shells to call home. When one crab finds that its current shell is a bit cramped, it begins looking for a vacant shell larger than its current one. If a crab finds a shell that meets its needs, it moves in, abandoning its old shell, which in turn becomes vacant and available to other crabs. If the availability of vacant shells is limited, a crab will focus its attention on a suitable larger shell even if it is currently occupied by another crab. If this second crab should come across an even larger vacant shell and moves out, almost instantly the first crab moves into the newly vacated shell.