Dolphin Watch
Oyster's pearl
By ANN WEAVER
| Article published on Thursday, Jan. 4, 2007 |
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![[Image]](/content_images/010407_out-01.jpg) |
| Photo by ANN WEAVER |
| Oyster surfaces with a fresh whelk (marine snail) egg case hooked around his dorsal fin. |
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Their constant grin suggests dolphins have a fun-loving nature to match, that they live in some sort of twilight zone world where they're always in the middle of a joke.
The dolphin grin isn't a grin, of course. It's a well-designed maw for those who catch food using only their mouths. But it forces the question: Do dolphins play? Are dolphins playful by nature?
Play is noteworthy because it's behavior in a class of its own. You don't need play to survive, which isn't true for other basic behaviors. It implies brains. Playing with a toy requires imagination. If you made the toy yourself, you're a toolmaker. Playing with another individual requires the recognition that we are, in fact, playing. Otherwise, the lunging, swinging and punching would have a very different meaning. At a minimum, you must recognize this. What does play suggest about dolphin mental abilities?
Dolphins are playful in captivity. Those lucky enough to have toys play like human kids at a playground. They whip Frisbees around, swim with balls in their mouths and twirl chains of bubbles they make themselves.
A skeptic could reasonably argue that captive dolphin behavior isn't normal, isn't representative, like people in a jail cell.
Dolphins are playful at sea too. One, they play with each other. We call this social play to distinguish it from object play. Most often, its the calves who poke and wrestle, leaping and toppling down on each other. On occasion, moms appear to play with calves.
Two, dolphins play with toys. They swim draped with seaweed and play Catch with sticks. They poke unsuspecting birds and toss hapless eels into the skies.
When calves do this, we call it object play. When adults do this, we interpret their behavior as feeding.
But should we? Consider the extraordinary moment this December when Oyster, a young adult male, surfaced with a fantastic object.
Oyster is an unusual local dolphin. We named him Oyster because we first saw him hunting over an oyster bed. Fleet and elusive, his small body was covered with scratches. But his dorsal fin was unmarked, which made it hard to recognize him again. His picture data entered our vat of 34600 photo-identification photos as a lone dolphin. Being alone is rare.
Over the months, we occasionally found small lone dolphins. One quiet morning, a small dolphin hunted alone off Eleanor Island; too small, I thought, to be alone. One evening last fall, a lone dolphin hunted around a channel marker off the Treasure Island Causeway; pole foraging is atypical. One pretty spring afternoon, a lone dolphin haunting John's Pass was eventually persuaded to provide a couple of pictures that revealed a nasty shark scar on the peduncle, the dolphin's 'tail', a definitive mark for later recognition. One beautiful summer's midday, a small lone dolphin galloped around the Treasure Island Causeway, elusive and alone. It too had a shark scar on the peduncle.
We came to call lone elusive dolphins 'The Phantom.' When I perused our vast photo identification catalogue to compare phantom dolphin pictures taken months apart, they were the same dolphin, Oyster.
Curiously, as I became able to identify Oyster in the field, he became used to our boat and more social with other dolphins as well, mostly young adults like he. Oyster rabble-roused around the waters, sometimes exploring for food and sometimes the mysteries of sex.
One fine December day, Oyster appeared at the boat with the ease of a dolphin familiar with our routine. He briefly swung by the boat and vanished. Given his years of elusive behavior, this was gift enough. But his next move was astonishing.
He surfaced again, draped with some sort of weird coiled yellow hose. I gasped through the camera's viewfinder. The yellow hose was a fresh whelk (marine snail) egg case, the longest I've ever seen. Then the waters were silent. We waited breathlessly.
He surfaced again. The coil was gone.
Then he himself sprinted across the bay and vanished.
I don't claim that Oyster has a fun-loving nature to match his constant grin or that he lives in the middle of some sort of twilight zone joke. But I do lay claim to yet another question: Was he being playful or just showing off?
Dr. Weaver studies wild dolphins under federal permit GA1088-1815, National Oceanic and Atmospheric Administration. Contact her at acweaver@tampabay.rr.com.
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Article published on Thursday, Jan. 4, 2007
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