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Dolphin Watch
Horsetails: A game or something else?
By ANN WEAVER
Article published on Thursday, Sept. 27, 2007
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![[Image]](/content_images/092707_out-01.jpg) |
| Photo by ANN WEAVER |
| This dolphin tosses a horsetail into the air and then plunges into the sea to catch it, seemingly playing a game. |
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Did you ever play the game of Horseshoes? You toss a horseshoe to hook it around a vertical stick. I remember how the metal shoes clanked when they hit.
The word horseshoes is like the word horsetails. Horsetails are mangrove seedpods. Long, thin and slightly curved, they look like so many brown pencils floating around the bays. Hundreds appeared by summer’s end.
The dolphins have been throwing them around all month. Like people play Horseshoes, dolphins do something we can call Horsetails.
It started the first of September. Capt John Heidemann and I had a bet that a certain dolphin would be in a certain place. So around suppertime we went out to settle the bet.
On the way, we found the dolphin P. The bet was not about P but we stopped to watch. She was hunting and mostly out of sight. Observation wasn’t gripping and it was getting dark. So we started to leave.
Suddenly, she poked her face out of the water, snapped her head sideways and sent a long thin horsetail into the air. She plunged after it and disappeared and reappeared with the horsetail. Tossing and retrieving, she looked like a small animated fountain in the middle of a darkening lagoon. We gawked. The more of a dolphin’s body you can see, the more compelling it is to watch.
P’s performance was one of those times when a dolphin starts doing something interesting just as you’re about to leave. She reminded me of a child who turns politically persuasive by doing something really cute just as you’re leaving the house. Whether this was P’s goal, I cannot say, but it wasn’t the first time.
The next day, we were stunned when N did the same thing. N is a bull. I guess I never thought that big ol’ burly bottlenose boys play with toys, especially around other bulls.
It’s easy to think that such ‘bull pens’ are seething with tension and ever ready to ignite a fight. Maybe they are. But in this respect, I think dolphins are like people: The potential for peace or war is always there; it just depends on the circumstances.
Like P the night before, N tossed and caught a horsetail several times as he traveled through the soft morning light alongside bulls DD2, BB, Cheetah and LA Cheetah. Cheetah is named after the endearing chimp actor in Johnny Weissmuller’s Tarzan movies. LA Cheetah is a Cheetah Look Alike, hence LA.
Later that morning, Cheetah and LA Cheetah meandered with females JJ and Rim past sandbars dotted with shorebirds poking for breakfast. Two more bulls came up. One of them started tossing horsetails. After two more bulls came barging in and out, breaking up the action, the first four returned to their meanderings.
This time, young Rim tossed horsetails two different times. The first time, she flipped the horsetail gently. The second time, after 15 minutes of kicking some fish around, she flung a horsetail for several minutes. Like calves, she got more and more excited until she lunged half her young body out of the water to whip the horsetail high in the sky.
A couple of weeks later, as it felt more like autumn, females P and DD1 foraged for food in shallow water. P grabbed a passing horsetail and starting throwing it around as two bulls approached. Then she tussled with the bulls, the horsetail forgotten.
Why are dolphins throwing horsetails around this month? Part of it is opportunity. The pretty little pencils are everywhere. After the fourth episode of Horsetails on Labor Day, John facetiously wondered if it was some kind of dolphin holiday ritual like humans buying potato chips on the 4th of July.
What made dolphin Horsetails appealing to me was that I’d been playing with horsetails myself.
Horsetails reveal patterns of wind and current. Weak winds and currents scatter them randomly; they float horizontally. Strong winds and currents assemble them in long lines in which they stand vertically. Pitching and bobbing at the surface, they look like the bewitched broomsticks in the animated movie Fantasia when Mickey Mouse was the Sorcerer’s Apprentice.
Horsetails might also be an interesting way to learn critical statistical concepts in the revision of my Good-Natured Statistics book (amazon.com). I collected a pile of them from my kayak, which was hilarious because kayaks are very tippy, and took a picture for the book. Then I measured their length.
Based on 156 of them, horsetails are about 7-8 inches long, give or take a couple inches; the smallest the length of your index finger and the longest a rocketing foot long (mean = 7.7 in, standard deviation = 1.7 in, range 3.1-12.6 in, N = 156).
Why bother? Well, we might be able to use the information to measure dolphins at sea without bothering them. If we know how long the average horsetail is, maybe we could guesstimate the size of dolphin heads or jaws (rostra) from pictures.
Finally, horsetail tossing illustrates the dilemma of using human behavior to explain animal behavior. Since we call the human behavior of tossing horseshoes the game of Horseshoes, why not call the dolphin behavior of tossing horsetails the game of Horsetails? After all, it looks like fun.
When humans do something similar, they’re playing, right? Like people play Horseshoes, dolphins do something we can call Horsetails. Or can we?
Related stories about these dolphins
A Particular Proximity, Barging in and out, Carrying on with Coastal Keep Away, Credible curiosity, Dawn of Knowledge, The urge to surge
Dr. Weaver studies wild dolphins under federal permit GA1088-1815, National Oceanic and Atmospheric Administration. Send her an e-mail at acweaver@tampabay.rr.com or visit www.dazzlingdolphins.com.
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Article published on Thursday, Sept. 27, 2007
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