The hiding Stingray. (KO) They flutter their "wings" in the sand to cover themselves on the ocean bottom. Good camouflage, and they nip up and nab small fish and other delicacies without being seen. Smart way to hunt with little effort.
A bait ball, or baitball, occurs when small fish swarm in a tightly packed spherical formation about a common centre. It is a last-ditch defensive measure adopted by small schooling fish when they are threatened by predators.