Ned Potter is the science correspondent for ABC's "World News with Charles Gibson." He has reported on such topics as space exploration, the human genome and climate change.
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Swimming With Sharks
August 01, 2007 6:01 PM
One of the nice things about science reporting is that one gets to meet interesting people, doing worthwhile things, who want to tell their stories.
So yesterday, we met Bertha.
Bertha is a sand tiger shark. She lives at the New York Aquarium, and Hans Walters, the man in charge there, is sure she's lived longer in captivity than any other shark in the world.
This is more than a point of pride for one aquarium. Fascinated as people seem to be with these top predators of the ocean, there's very little data on what their lifespans are.
"Bertha’s going to tell us how long these guys live," said Walters when we did our interview next to Bertha's tank. "I don’t think anybody has come up with any hard evidence on how long sharks live. Well, Bertha, who came here as a pup in 1965, is now 42, so she’ll show us. As long as we have her, we’ll know."
It happens to be "Shark Week" at the Discovery Channel, and I was asked to see if there was some interesting science we could add to an already-interesting subject. Some items that came up:
--Sharks, of the superorder Selachimorpha, have been around for about 450 million years.
--There are about 350 different species, most of them less than three feet long as adults.
--Like many other fish, many shark species have a sixth sense: they can pick up the minute electrical charges generated by the body of a fish a few feet away. Very useful, along with their exquisite hearing, eyesight and sense of smell, for homing in on prey.
The behemoths made famous by the movies are relatively recent. Until the end of the Cretaceous Period (the last of the dinosaurs), the top aquatic predators were probably marine reptiles, and only when they disappeared was there a niche for large sharks.
Biologists regard modern sharks as an evolutionary success story. They're very efficient in the water, they don't waste a lot of energy, and they've adapted to changing conditions. Among the many places to look are HERE and HERE.
Why are there a gazillion shark sites on the web? That probably has more to do with human psychology than shark physiology. (One good laugh: I searched for "SHARK" in capital letters, found, among other things, a Wikipedia entry on software encryption. Try lowercase.)
I asked Hans Walters about his own interest. "What do little boys like?" he said. "They like fast cars, motorcycles, big dangerous things. Dinosaurs, large predators, sharks. I’m the little kid that never grew up."
Oh, one last thing that bears repeating: We were reminded by several scientists that worldwide, sharks attack human beings fewer than a hundred times a year.
August 1, 2007 | Permalink | Share | User Comments (4)
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Just how do scientists track shark attacks. I imagine if a large shark attacks a human in open water, there's usually not anyone left to report an attack
Posted by: KM | Aug 2, 2007 2:05:11 AM
It seems we as a species have a certain fascination for sharks, as witnessed by the numerous articles, movies, and other media which are concerned with them. Who can ever forget the personification of sheer menace which the shark portrayed in "Jaws"?
Posted by: chuck | Aug 2, 2007 8:37:10 AM
Fascinating creatures - been around for as long as the cockroaches. Fortunately, the roaches don't get as big as the Great Whites, although I have seen pictures of some 6-inchers. I can still remember the look on Roy Scheider's face in "Jaws" when he said, "We're going to need a bigger boat."
Posted by: Andy | Aug 2, 2007 10:37:42 AM
I love sharks. Always have. Truly fascinating creatures. And KM, attacks are tracked and documented by a large database in Hawaii, I think it's in Hawaii. Of course reports from third world nations is hard or non-existant.
Posted by: Lawrence | Aug 2, 2007 8:56:58 PM
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