In strips and cartoons air bubbles are usually represented by circles. That is wide of the truth. On the topside they are indeed spherical, but on the bottom they are rather concave and set in a peripheral aura of dancing bubblettes. If they are not too deep I sometimes visit divers and ascend gloriously among their bubbles to the surface.
Dusty surprised Verena by blowing a large air bubble underneath her in which she saw her own reflection. She wondered if Dusty had done this on purpose so she would be aware of this mirror effect. I can surface before my own bubbles do, so Dusty can easily out swim hers and watch her own image.
The Hawaii based dolphin researcher Ken Martin demonstrated experimentally that dolphins recognize their own reflection. He let a dolphin look into a mirror and next showed a previously taken video of the same animal. In the first case the dolphin reacted to its image by performing movements it could recognize as its own. Martin calls these 'contingency checks'. In the second it watches rather unmoved. So the chance that Dusty intentionally blew a looking-glass bubble can definitely not be excluded.
Also Verena witnessed how Dusty threw swimmers, who tried to take her play-bottles, into confusion by blowing a big cloud of air bubbles.
There are countless examples of how dolphins and whales 'handle' air. Quite recently it has been discovered that humpbacks blow a bubble curtain around a swarm of plankton or a shoal of fish. Inside they drive their prey to the surface to dispose of them in one giant swallow.
Aforementioned Ken Martin also drew attention to the ring bubbles dolphins can originate. In the delphinarium of Duisburg I once saw a dolphin swim towards me before the glass wall of the trainers room. She kept suspended right before me and formed, with a short nod of her head, a true round ring of air in the water. This revolved around its circle axis and ascended slowly.
A Dutch TV-documentary on Ken Martins research does not only show dolphins making ring bubbles alone, but also in concerted action. That they swim through their own ring bubble, that they are capable, possibly with sound, to push their bubble downward, that they can make one by brushing their fluke at the surface or fill a corkscrew shaped whirl, created with their dorsal fin, up with air.
Actually it is not so surprising, that dolphins use air as a medium for play, communication and hunting. Air is of such vital importance to them that it must be a subject of careful consideration. The results of that are miraculous and astounding. They give us a breathtaking conception of their fantasy, creativity and technological insight. And these are things we can understand because we can see them. But there will be plenty of bubbles left.