 Small whales are known to engage in complex play behaviour , which includes such things as producing stable underwater toroidal air @-@ core vortex rings or " bubble rings " . There are two main methods of bubble ring production : rapid puffing of a burst of air into the water and allowing it to rise to the surface , forming a ring , or swimming repeatedly in a circle and then stopping to inject air into the helical vortex currents thus formed . They also appear to enjoy biting the vortex @-@ rings , so that they burst into many separate bubbles and then rise quickly to the surface . Some believe this is a means of communication . Whales are also known to produce bubble @-@ nets for the purpose of foraging . 
