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Dolphin Watch
Powersharking
By ANN WEAVER
Article published on Wednesday, June 28, 2006
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![[Image]](/content_images/062806_out-01.jpg) |
| Photo by ANN WEAVER |
| Sharking is when a dolphin slowly glides just under the water surface so its dorsal fin remains visible. |
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Dolphins are smart. How do they use their brains at sea? It starts with feeding. If you're smart about feeding, you have a competitive advantage to pass onto your children.
In our study area, competition over food is probably fierce. At least 200 dolphins use the area. Some live here. Others only visit. They share the area with any number of other large predators. All of them have to eat.
Last fall, an incredible display of dolphin speed, agility, cooperation and something else suggested how smart some dolphins can be. You decide.
Usually you can't see dolphins feeding because they feed underwater. Sometimes, feeding is exhilaratingly visible, like when they powershark.
Powersharking is an unbelievably athletic version of sharking. It's a version of behavior called sharking. Sharking is when a dolphin slowly glides just under the water surface so its dorsal fin remains visible. It's the behavior movie makers use to portray marauding sharks - a fin slicing the surface to the thump of menacing music - so sharking is a good name for the behavior.
Sharking dolphins are hunting. They often start slowly. When sharking dolphins accelerate explosively after prey, sharking becomes powersharking. Fish veer desperately. Dolphins swing madly in pursuit. Riveted, you feel for the frantic fish.
Dolphins powershark alone and in groups. Group powersharking shows their cooperative nature like wolves relaying fated moose in the icy north. As with wolves, group powersharking may yield more food than a single dolphin could catch alone. That's a competitive advantage. And it takes brains.
One overcast morning, a tight-knit nursery group traveled between the channel markers in the north end of our study area. They veered towards some mangroves. The water got shallow fast. In about 3 feet of water, the calves stopped to play. A subadult, Stick, babysat the cavorting calves. Two moms kept going toward the mangroves. Moving parallel to the shoreline in 20 inches of water, they started sharking in rhythm about 6 feet apart.
You could almost hear a drum beat. Sharking means drama.
Another mom torpedoed in from the right and swung into formation. Side by side, the three mothers accelerated in unison, quadrupling their speed in seconds.
Faster and faster and faster they went. "Wow!!" we cried. Great rooster-tails of water sheered off their sides as they sliced the surface at speed! We gunned it to stay with them, hovering dozens of yards away to avoid disrupting them.
Suddenly, one of the dolphins kicked a fish over her head like a running soccer player punting a ball. The fish slammed onto the water ahead. The trio overtook it. We assume someone ate it. The dolphins sped on. Another kick. Another fish flew and dropped. The powersharking dolphins kicked up frenzied fish for several minutes without missing a beat. Whose fish was whose? How did they share the food?
Two kayaks lulled in the mists beyond. Animated by rooster-tails roaring into view, the kayakers rushed after the trio. One kayak, by design or mistake, cut in front and ran the dolphins over.
The fever broke. Action stopped. Sequence shattered, the dolphins milled.
A dolphin surfaced next to the kayak. The kayakers yelled with delight. It turned and smacked the kayak with its tail! You decide.
Dr. Weaver studies wild dolphins under federal permit GA1088-1815, National Oceanic and Atmospheric Administration. Contact her at www.dazzlingdolphins.com.
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Article published on Wednesday, June 28, 2006
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