So how do the dolphins make those bubble rings (previous post) that seem to defy what we know about physics? According to a Scientific American article on the subject, the dolphins are able to create and control the movement of the rings by controlling the movement of the water around their own bodies.
Probably the easiest way to visualize this is to think of a whirlpool, similar to what is created around the drain of a bathtub when we let the water out, except in this case the vortex consists entirely of water.
But how do the dolphins know where the vortexes are once they make them? Scientists think the dolphins "see" them by using their sonar, and the implications of that are stunning.
Because we know that some of the brain structures of odontocetes (toothed whales and dolphins) are arranged in such a way that what they "hear" might be easily processed in the same parts that process what they see, it is not surprising to understand that at least some of the cetaceans actually create mental pictures of what they detect with their sonar. And although most of us don't think of it that way, oceanographers know that the ocean is not a uniform body of water at all, but a complicated mass of layers and swirls. So if you think about it, what we see as uniform in texture and varying only in light and temperature – how we see the ocean - could be perceived, or 'seen', by the cetaceans in much greater complexity.
If you add to that the fact that some of the dolphins and whales most likely 'see' underwater shapes of currents and vortexes with their sonar,though, you begin to understand their amazing adaptation to the richness of their ocean world.
In our next post, we'll talk about how our local orcas may use these properties of water and sound in their search for food.