Wednesday, July 22, 2009

How Dolphins Make The Bubble Rings

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.

Whirlpool (Creative Commons Photo)
After first creating the whirling vortex of water with their body motion, the dolphins then blow a huge bubble of air such that the water vortex pushes through the center and traps a ring of bubbles around it's edges. The dolphins then continue to manipulate and control the water… and thus control the bubble rings.

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.

Much like we can see these shafts of light, dolphins can "see" water layers with sonar (Creative Commons photo).

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.

In the presence of algae or plankton, we too can see water motion (Creative Commons photo).

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.

Photo by Erin Heydenreich

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.

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