I blogged this video last year, and at the time was puzzled at how a ring of air could move horizontally through the water. Today Reddit had a link to this explanation:
Dolphins create bubble rings by blowing air in a water vortex ring: by flipping a fin they create a vortex ring of water. The then blow air in the ring, which goes to the center of the vortex ring. In the water vortex ring the natural location of the air is in the center of the vortex. When air and water move in a circular path like they do in the vortex ring, air and water are separated due to the centripetal force. Since density of water is larger than air, water moves at the outside, while the air ends up in the middle.The source is Deep Ocean Diving, where there is additional information and photos. Apparently human divers are capable of learning this trick from dolphins! (And what's uber-cool about the air rings in the video above is that is is not a behavior taught to the dolphins, but rather a spontaneous form of play!). I love the video.
Indeed, it is very cute, But the sad thing is that only dolphins in captivity do it, and a lot of scientists think it's because they get bored.
ReplyDeleteAnyhow, it's a nice way to amuse themselves!