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Dolphins play with rings.
The attached video is of dolphins playing with silver colored rings which they have the ability to make under water to play with. It isn’t known how they learn this, or if it’s an inbred ability. As if by magic the dolphin does a quick flip of its head and a silver ring appears in front of its pointed beak.
The ring is a solid, donut shaped bubble about 2-ft across, yet it doesn’t rise to the surface of the water! It stands upright in the water like a magic doorway to an unseen dimension. The dolphin then pulls a small silver donut from the larger one. Looking at the twisting ring for one last time a bite is taken from it, causing the small ring to collapse into a thousands of tiny bubbles which head upward towards the water’s surface. After a few moments the dolphin creates another ring to play with. There also seems to be a separate mechanism for producing small rings, which a dolphin can accomplish by a quick flip of its head.
An explanation of how dolphins make these silver rings is that they are ‘air-core vortex rings’.
Invisible, spinning vortices in the water are generated from the tip of a dolphin’s dorsal fin when it is moving rapidly and turning. When dolphins break the line, the ends are drawn together into
a closed ring. The higher velocity fluid around the core of the vortex is at a lower pressure than the fluid circulating farther away. Air is injected into the rings via bubbles released from the dolphin’s blowhole.
The energy of the water vortex is enough to keep the bubbles from rising for a reasonably few seconds of play time. also: The young dolphin gives a quick flip of her head, and an undulating silver ring appears–as if by magic–in front of her. The ring is a solid, toroidal bubble two feet across–and yet it does not rise to the surface! It stands erect in the water like the rim of a magic mirror, or the doorway to an unseen dimension.
For long seconds the dolphin regards its creation, from varying aspects and angles, with its vision and sonar. Seemingly making a judgment, the dolphin then quickly pulls a small silver donut from the larger structure, which collapses into small bubbles. She then “pushes” the donut, which stays just inches ahead of her rostrum, perhaps 20 feet over a period of up to 10 seconds. Then, stopping again, she regards the twisting ring for a last time and bites it–causing it to collapse into a thousand tiny bubbles which head–as they should–for the water’s surface. After a few moments of reflection, she creates another.
This isn’t fantasy, it’s real. And it isn’t magic, just marvelous. It is a rare dolphin behavior, and we first saw it in the play of two baby dolphins. It gives us a little more insight into the superb level of control dolphins can exercise on their water environment, and underscores the fact that we can still discover things about dolphins by simply watching them.
A better and more rigorous explanation–by Hans Ramm at Scripps Institute of Oceanography. The silver rings, as it turns out, are “air-core vortex rings”, and the helices are a similar phenomenon. Invisible, spinning vortices in the water are generated from the tip of a dolphin’s dorsal fin when it is moving rapidly and turning.
According to Hans: “Being unstable without a boundary nearby, the vortex line tends to form into a more stable form such as a helix. When the dolphins break the line, the ends are drawn together into closed rings. Owing to the Bernoulli effect, the higher velocity fluid around the core of the vortex is at a lower pressure than the fluid circulating farther away. Air is injected into the rings via bubbles released from the dolphin’s blowhole.” The energy of the water vortex is enough to keep the bubbles from rising for a reasonably long period–on the order of 10 seconds. There also seems to be a separate mechanism for producing small rings, which a dolphin can accomplish by a quick flip of its head.
Creation of these rings by dolphins isn’t new. (far from it–dolphins were probably blowing magnificent silver rings while our ancestors were hanging off tree limbs). It does seem to be a relatively rare behavior, though: it has been seen before only in a specific group of dolphins documented by Diana Reiss and Jan Ostman at Marine World. “The fact that ring-blowing is rare and that we have two babies doing it suggests that one baby learned it from the other”, comments Ken Marten. “Whether it was a case of observational learning, or one “taught” the other, we don’t know… but it’d sure be interesting to know.”
The social situation also seems to affect ring-blowing: The babies made them most intensely when they were the only two dolphins in the tank and when there was only one adult. The behavior stopped entirely when they were outnumbered by adults.
The reaction to our documentation of these rings has been universal–people are fascinated by them. Dr. Ken Norris, the world’s leading expert on dolphins, had never seen it before. Robert Wolff of Apple Computer’s Advanced Design Group made a “quicktime” movie of ring-blowing for display on Mac computers. Arthur C. Clarke, Earthtrust Advisory Board member, thought they were wonderful–but debated my offered contention that they might be the first “extraterrestrial art”, pointing to interesting “artistic” achievements by other nonhuman animals.
via earthtrust
Maureen Adams
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