Dolphin bubble rings

Something a little different today. I came across an amazing video I thought people might like to see. It features a dolphin making a bubble ring, and then seeming to play with it.

Quotes and comments;

A. 'The video shows various dolphins creating rotating bubble rings which seem to hover in the water for a few seconds. The dolphins do this by first creating a water vortex with their dorsal fin. The ends of the vortex then come together into an invisible ring. Then the dolphin injects air from its blowhole into the spinning vortex. The vortex has enough energy to hold the ring from rising too quickly for play. Such a vortex bubble is about two feet across. [1.]

B. Video link is here; Snopes.com

C. ' However, dolphins might play with the vortex to create a smaller ring. Sometimes a dolphin will insert a smaller bubble ring inside a larger ring. They also create rings that flip vertically or even flip completely over. Sometimes a dolphin will create two bubble rings that collide and produce a third ring. The video shows one dolphin creating a large ring and watching it rise through the water. Just before the ring breaks the surface, the dolphin swims through the ring and leaps from the water. [1.]

- The dolphin in the video appears to be playing with the bubble ring. I got to thinking about this and wondering what was going on. Is it possible that these bubble rings originally served the purpose of catching various forms of sea life? Is there a connection with the 'rings' whales use to catch krill? I wonder if this was originally part of an 'instinctual' design for catching fish, and that through some mutation the dolphins have 'lost sight' of what the rings are for?

If this isn't the case, I wonder if the rings originally serve some other purpose that's been lost. (It may be that there is a purpose that we don't yet understand.)
- It may be that this is purely a form of play, or has some use in teaching the young various techniques that are useful.

Notes;
1. Dolphins at play - Creationmoments.org