Dolphin Bubble Rings

It seems that a couple of years ago a few dolphins, mostly female, began to blow bubble rings at Sea World in Orlando.  Once started this behaviour has spread to others.

At first I wondered if this was a carefully crafted hoax as the rings seem so improbable.  Not so, this is genuine and has been the subject of one scientific publication.

I have not been able to find a good explanation of the physics of the rings.  It would seem reasonable that they depend upon the air spinning to maintain their structural integrity.  I am not sure if a vortex is also required in the surrounding water.  They are rising when left to themselves although the camera angles make this difficult to see. 

Enjoy the video.

Video Credit: Chiajungchi, YouTube. Dec.16, 2007.  Musics "No one is alone in the woods" (John Williams). Boston Pops.