If you look closely you'll notice little holes here and there on the beach, with little bits of sand and whatnot near them, like this. These holes are the burrows of Ghost Crabs (also known as Sand Crabs).  You don't usually see the actual crab, because by the time you've spotted the little hole, the crab has long since spotted you and zipped inside. These crabs are very small and quick, and they match the color of the sand exactly.

Can you spot the crab?

Here is a video of a Ghost Crab at its burrow.  My apologies for the wobbly camera-work; I'm zoomed all the way in so as not to scare the crab away.

Thank you David for composing the music for my video!