Apparently, both dolphins and certain whales are known to blow bubble rings. Two ways of creating such rings have been reported: one way is by letting a ring out of their blow hole, the other by creating a water vortex ring and blowing air in the vortex ring.
There are few ways that bubble rings can be created:
- Rings can be created by letting air escape through an orifice that is opened and closed abruptly. A bubble-blowing diver falls in this category.
- Rings can be created by letting a fixed amount of air escape through an orifice that is permanently opened. The bubble machine of David Whiteis falls in this category
- Dolphins create bubble rings by blowing air in a water vortex ring. They create a vortex of water by flipping a fin. They then blow air in the ring. The air goes to the center of the vortex ring. 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 the density of water is larger than air, water moves at the outside, while the air ends up in the middle.