Beachcombers heading for the Texas coast for last-minute summer fun need not panic. They’re more likely to strike it rich in the Texas Lottery than strike out with a shark, according to a Sea World shark expert.
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| Gary Violetta (Sea World photo) |
Gary Violetta, a curator of fishes at Sea World of Orlando, said 100 million sharks were killed in 1993 compared to the 100 reported shark bites and the 25 shark-related deaths the same year. Also in 1993, 250 people were killed by elephants and 1,250 people sided from bee stings, he said.
Sharks are relatively harmless and stay clear of divers if alone, Violetta said.
“Most shark bites are provoked,” he said. “They are not after anyone.”
Violetta, who previously worked at Sea Word San Antonio, said most people will try and grab a shark’s tail as it swims by, causing it to defend itself. Also, spear fishermen are prone to shark attacks by leaving their caught fish dangling by their side on a stringer. The sharks are attracted to the oil and blood streaming off the dead fish, he said. Most shark attacks occur in 5 to 6 feet of water. People should be more consented with getting stung by a Portuguese man-of-war, he said.
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| Hamerhead shark (Barry Peters photo) |
Sharks indigenous to the Texas Gulf Coast are hammerheads, Atlantic sharp nose sharks, black tip sharks and bonnetheads.
Sharks are the top predator in the ocean, Violetta said, because they’re well adapted to their environment and they have existed for more than 350 million years constantly evolving ever since.
Their bodies are equipped with special sensing cells congaing fluid which help sense low-level vibrations in the water. These cells are located in an area called the lateral line on the shark’s back. More sensing cells up front around the shark’s snout, called the ampullae of Lorenzini, pick up electromagnetic impulses from a potential meal.
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| Atlantic sharp nose shark (NOAA photo) |
The 350 species of sharks which exist on the planet have keen eyesight, Violetta said, with some species able to see color.
The shark population has been declining because of over fishing and the senseless slaughter of sharks, he said, but Violetta believes the shark population will recover.
Violetta believes the movie “Jaws” did more to decrease the shark population.
“It gave them a bad rep,” he said.
The movie, based on the Peter Benchley novel of the same name, featured a so-called rogue great white shark terrorizing the waters off Long Island, New York.
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| Blacktip shark (Albert Kok photo) |
Female sharks produce two to 50 pups once or twice a year, he said, taking seven to 10 years to mature. Sharks in general live about 30 to 35 years. Sea World Currently concentrates their efforts on education rather than research, Violetta said, adding education is the key to keeping sharks off the endangered species list.
He said, however, researchers in Sarasota, Fla., have used sharks in cancer research because they believe the shark’s cartilage prevents them from developing cancer.
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| Bonnethead shark (Matt Howry photo) |
Researchers have not proved the cartilage prevents cancer, and Violetta fears more sharks will die from the false hope they provide a cure.
Forty years ago, little was known about sharks, he said, adding he believes more needs to be learned from both laboratory and field study.
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Sidebar—The Shark Lady
When I was a mere pup, about eight years old, the movie “Jaws” had just come out. My mom, being overly mindful of what I saw on TV and at the movies, forbade me from watching it. Come to think of it, I actually didn’t get to see “Jaws” until a couple years later with a friend who had cable TV at his house. Either way, it made an impression.
I had to settle on the occasional Jacques Cousteau television special (no Discovery Channel back then) or book or filmstrip at the library at Colonial Hills Elementary school to learn anything about sharks. So began my foray into marine biology. My school had a book fair one day. I got lucky and discovered a book about a woman who swam with sharks in order to learn more about them.
The name of that book—“Shark Lady: True Adventures of Eugenie Clark.” I relished reading that book and imagined myself swimming along side, sharing in her adventures. Dr. Clark, 92, an ichthyologist (one who studies fish) became inspired by her trips to the then Battery Park Aquarium, now known as the New York Aquarium. She would grow up to conduct extensive underwater research with fish and sharks, and even pioneered scuba diving for research purposes.
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| Dr. Eugenie Clark (2011 U.S. Dept. of Labor photo) |
One particular chapter of the book described her research in the Red Sea. She learned a certain fish that swims there, scientific name Pardachirus, known there locally as the Moses sole, secreted a milky substance that made her hand feel numb and tingly.
She observed when sea urchins, starfish, and reef fish were exposed to small doses of this milky substance, it killed these creatures quickly. She wondered how it might work on sharks. So, she experimented on three reef whitetip sharks she had access to at the lab where she worked. She placed the moses sole inside the tank with the sharks. The hungry sharks swam in for dinner time, but when they got close to the fish they suddenly turned away, shaking their heads as if trying to get a bad taste out of their mouths.
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| Moses sole (Victor Cebollada photo) |
Dr. Clark repeated the experiment and observed the sharks would avoid the Moses sole each time. Since then, researchers have tried to create an effective shark repellant based on the Moses sole secretion, which has a compound now known as paradaxin, a neurotoxic peptide. This compound is very difficult to handle and loses its effectiveness after a time when frozen or exposed to room temperature. Nevertheless, researchers continue work to create an effective shark repellant, all because a woman scientist took the time to explore the possibility.
I didn’t think much of it at the time, but it didn’t matter to me that she’s a woman. I knew girls could do things better than me ever since kindergarten, and I didn’t have a problem with that. I just knew I wanted to do something as cool as swimming with sharks. But first, I had to learn how to swim (a story for another time).
If only we could do more to eliminate the gender boundaries and not automatically think “man” or “woman”—just think “human.”
©2014 Martin Malacara
