Can you explain to me how Dolphins create those underwater rings, with which they play?

Please watch this video showing Dolphins swimming in a tank, creating these rings with which they play.

Someone sent me the video link, but didn’t offer me any explanantion, and I’m kind of embarrassed to admit my ignorance about this phenomenon, because over 20 years ago, I assisted a woman who trained Dolphins to perform simple tricks for public performances, and I never saw them do this in their tank, probably because they were always distracted by their training regimen.

I will tell you that, during my brief exposure to them, I found them to be incredibly friendly and highly intelligent. I felt a sense of peace and overwhelming love from them, and yet at the same time, I was worried about their trust of humans, because some of us are not worthy of their trust, nor their love.

They are majestic and gentle creatures, and the stories of how they will come to the rescue of a stranded swimmer (and will even attack a shark, who is approaching a swimmer), are legendary.

If I may be allowed to “plug” an organization that loves them and champions their cause, please visit the website of International Dolphin Watch, where I hope you will “fall in love” with these saltwater friends of ours, as I have…