Yesterday I noticed a strange animal behavior as I scanned Reeds Beach through my camera viewfinder. A group of laughing gulls was bobbing up and down from time to time. I thought it was due to camera shake, but I had the camera on a tripod, so that had to be ruled out.
Finally I remembered reading about that particular behavior. As you know, the gulls and other birds eat the eggs freshly spawned and buried in sand by female horseshoe crabs. The gulls have learned that they can get at the deeply buried eggs by stamping on the sand as the waves come in. Then as the waves recede, the disturbed sand is carried out to sea, revealing and leaving the eggs behind. Those smart gulls are laughing all the way to the bank.
The following photo shows the gulls stamping. Note that the water was coming in and the gulls had their heads up in the air. That long pointed thing sticking out in the middle of the picture was the tail of one overturned crab.
Six seconds later, the water had receded and all the gulls had their heads back down, eating crab eggs. Note the overturned crab tail was still there among the gulls.