We’ve all seen it in a movie: A small group of people are swimming in the sea. Someone gets hurt, blood touches water, and instantly sharks appear who then devour the party in a ruthless and very painful way. But how fast does the odor or taste of blood go in water? Am I right to believe that it takes a while for a shark a mile away to taste it?

As you probably know already, sharks are pretty well suited to this whole predation thing. They have excellent hearing in the low frequencies and can pick out the sound of something thrashing around in the water well over 1,000 feet away. They’re also outfitted with sensory cavities called the ampullae of Lorenzini, which register the faint electrical fields generated by living bodies. And then there’s the shark’s sense of smell, which though not quite as phenomenal as was once believed (you used to see a stat claiming that 70 percent of a shark’s brain was devoted to olfaction, which seems to have been a real overstatement) is still plenty acute: sharks can detect some chemicals at concentrations of around one part per 25 million, and experts claim they’ve seen sharks go nuts over a single drop of blood in a 2,000-gallon tank. (…)

A chemical (and for our purposes, blood) disperses in water via diffusion and mixing. Diffusion is a random and relatively slow process by which a concentrated group of molecules drifts apart, and in still water that’s the main way an odor would spread. But the ocean isn’t still, and so the primary determinants for how scents travel through seawater are the churning of waves and the flow of currents. For this reason, a shark’s standard response upon smelling something yummy is to swim into the prevailing current, as this will likely lead to the source; often it’ll home in by swimming in a series of decreasing spirals. The upshot is that while a shark would likely have to catch some breaks dispersalwise to identify the scent of blood a mile away from ground zero, at a distance of a quarter mile it’s got a decent shot at picking up some dinner.

OK, so: You and your pals are out in the ocean, bleeding away; the prevailing tidal current is somewhere around one meter per second, or 2.24 miles per hour. If a shark is upcurrent from you, it might take a while for the pertinent molecules to drift into its range. But if the shark happens to be fortuitously positioned a quarter mile downcurrent, the scent of blood could find its nostrils in a little under seven minutes. Midsize sharks have been clocked swimming at 24.5 mph, so conceivably if our specimen got a particularly good read it might take only a minute or so to locate you, giving us roughly an eight-minute gap between blood entering the water and shark cruising up with a bib on.

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{ Kazushi Takahashi’s tuna and shark metal sculptures | Kazushi Takahashi | via Ping Mag }

Perhaps the largest great white shark ever caught was off Malta, in the Mediterranean Sea, in 1987. It was reported to be 23 feet long and weigh 5,000 pounds. (Many scientists are skeptical and put the maximum length for a great white at closer to 21 feet.) A sea turtle, a blue shark and a dolphin, and a bag full of garbage were found in the giant’s innards.

The great white shark is a top predator throughout the world’s temperate and subtropical waters. It’s found most commonly off South Africa, New Zealand, Australia and the United States, where most sightings occur in the waters off California and the mid-Atlantic coast. With its torpedo shape and heavily muscled tail, a great white can swim 15 miles per hour or faster when attacking. It has about 240 serrated teeth in up to five rows. No one has seen great white sharks mate. (…)

Kock and other researchers claim that the shark has been defamed: its reputation as a ruthless, mindless man-eater is undeserved. In the past decade, Kock and other shark experts have come to realize that sharks rarely hunt humans—and that the beasts are sociable and curious. Unlike most fish,” Kock says, “white sharks are intelligent, highly inquisitive creatures.”

{ Smithsonian magazine | Continue reading }

A shark killed an American tourist surfing in western Mexico, police said on Tuesday, the second fatal attack along North America’s Pacific coast in four days.

A shark bit 24-year-old San Francisco resident Adrian Ruiz in the leg on Monday, opening a 15-inch (38-cm) wound. (…) “He was rushed in a bystander’s vehicle to the military naval hospital, where he died soon after from blood loss,” the statement said.

On Friday, a 66-year-old man was attacked and killed by a shark in the ocean near San Diego in the United States, the first person to die in a shark encounter off Southern California in nearly 50 years.

Fatal shark attacks in Mexico are also uncommon. The last one was in the Caribbean in 1997, according to the Florida Museum of Natural History’s International Shark Attack File. No one has been killed by a shark on Mexico’s Pacific coast in over 30 years.

Attacks on the Atlantic coast are more frequent, especially in Florida, which has about 25 to 30 a year. Last year, the only fatal shark attack in the world was in New Caledonia, in the southwest Pacific

{ Reuters }

Sharks generally rely on their superior sense of smell to find prey. Some species can smell one molecule of blood in over one million molecules of water - that’s equal to one drop of blood in 94 liters/25 gallons of water.

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A 5-foot-long shark scared hundreds of swimmers out of the water, but on Sunday its lifeless body washed ashore.

The thresher shark frightened crowds at Rockaway Beach, NY on Saturday as it splashed along the Long Island shore.

Although it wasn’t believed to be a threat, hundreds of swimmers left the water and authorities closed a 10-block stretch of beach for hours. The fish even came ashore at one point and several beachgoers pushed it back into the water.

On Sunday morning, the dead shark washed ashore, and beaches in the area were reopened.
“It is now safe to go back into the water,” said Parks Commissioner Adrian Benepe.

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Veterinarian Bob George sliced open the dead shark and saw the outline of a fish. No surprise there, since sharks digest their food slowly.

Then George realized he wasn’t looking at the stomach of the blacktip reef shark, but at her uterus. In it was a perfectly formed, 10-inch-long shark pup that was almost ready to be born.

He had been examining the shark, Tidbit, to figure out why she reacted badly to routine sedatives during a physical and died, hours after biting an aquarium curator on the shin. Now there was a bigger mystery: How did Tidbit get pregnant?

Sharks only breed with sharks of the same species, and there were no male blacktip reef sharks at the Virginia Aquarium & Marine Science Center in Virginia Beach.

Could Tidbit have defied nature, resulting in the first known shark hybrid?

The other possibility was that Tidbit had conceived without needing a male at all.

A recent study had documented the first confirmed case of asexual reproduction, or parthenogenesis, among sharks: a pup born at a Nebraska zoo came from an egg that developed in a female shark without sperm from a male. { The Guardian/AP | Continue reading }

In this Long Island fishing hamlet, hundreds of adults drank beer and children marveled at the bloodied sharks caught in a fishing contest, including a heart from a gutted 180-pound (82-kg) thresher shark that several children poked with awe.

A banner that flew overhead read “Enter the Cruel Shark Tournament Now.” It belonged to a smaller group protesting what they said was the killing on Friday and Saturday of a species that was already declining in number.

The small group of protesters, backed for the first time by a large U.S. animal protection group, want to stop the shark-hunting tournament, one of the largest in the United States where the winner can take home more than $400,000 in prize money and from bets placed among fishermen. { Reuters | Continue reading }

Their “high-falutin’ science,” as staff biologist Stephanie Leggett called it, involved catching juvenile bull sharks to determine the health risks prescription drugs pose to wildlife in the Caloosahatchee River.

Specifically, they’re investigating cholesterol-lowering drugs such as Lipitor, synthetic estrogen from contraceptives such as Ortho Evra, and antidepressants such as Paxil and Prozac.

Although pharmaceuticals are constantly flushing into coastal systems, mainly from human excretion through wastewater discharge, research on the effects is sparse. (…)

After 43 empty hooks, the team pulled a 3- to 4-year-old male bull shark on deck — bull sharks are very aggressive and considered by many scientists to be the most dangerous shark in the world, but often when hauled on board or brought to the side of a boat, they’re remarkably docile.

During the next 10 minutes — the fish was in a live well for two of those minutes — the researchers measured it (54 inches), took 6 milliliters of blood to test for drugs, clipped a small piece from the top of the dorsal fin and inserted a tag at the base of the dorsal fin — silicone-rubber discs on the tag absorb pharmaceuticals from whatever water the shark swims through. Then the shark was put back in the water. (…)

Researchers at the University of Georgia have found that low-level exposure to a widely used group of antidepressants, which include Prozac, Zoloft and Paxil, delays both development in fish and metamorphosis in frogs. { News Press | Continue reading }

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{ Damien Hirst, The Physical Impossibility of Death in the Mind of Someone Living, 1991 }

Damien Hirst (born June 7, 1965) is an English artist and the leading artist of the group that has been dubbed “Young British Artists” (or YBAs). He dominated the art scene in Britain during the 1990s and is internationally renowned. Death is a central theme in his work. He is best known for his Natural History series, in which dead animals (such as a shark, a sheep or a cow) are preserved, sometimes cut-up, in formaldehyde. His iconic work is The Physical Impossibility Of Death In the Mind Of Someone Living, a 14ft tiger shark in formaldehyde in a vitrine. Its sale in 2004 made him the second most expensive living artist (after Jasper Johns).

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Damien Hirst’s pickled shark, the most valuable and iconic symbol of the 1990s boom in conceptual art in Britain, is rotting and is likely to be swapped for a fresher specimen.

Steve Cohen, The American hedge fund multi-millionaire bought the shark for £6.5 million less than two years ago. But the 14ft tiger shark, suspended in a tank of formaldehyde, is deteriorating rapidly because of the way it was originally preserved by Hirst. The solution is now murky and the shark is showing considerable signs of wear and tear and has changed shape.

Its condition highlights growing alarm over how to preserve the high-priced conceptual works, many made from organic materials, poor quality paint, junk and even blood and insects, produced by Hirst’s Young British Artists movement.

If the shark substitution goes ahead, it will also raise serious questions about what is an original work of art, and whether changing parts of it devalues it. (…) In a frank admission about the longevity of some of Hirst’s works, Science, the company the artist runs to help him make his installations, said in a statement to The Art Newspaper: “Damien will happily help to refurbish [the shark] as he would with any of his works that are over 10 years old.”

The physical impossibility of death… was commissioned from Hirst by Charles Saatchi for £50,000. It remained the centrepiece of Mr Saatchi’s collection until he sold it to Mr Cohen in a deal brokered by the Gagosian Gallery in 2004. (…) When he purchased the shark, Mr Cohen was reported to be planning to donate it to the Museum of Modern Art in New York. Rumours there have suggested that the museum turned it down because of its condition. Mr Gagosian said: “Steve Cohen is very happy with the piece and is not troubled at all with having to substitute it. “It’s not a direct analogy but if you have a work by Dan Flavin [the American installation artist who uses fluorescent light tubes] and one of his lights goes out and you substitute it, it doesn’t matter. “It doesn’t affect the significance of the piece or the value of the piece.”

Formaldehyde may have been the wrong chemical for Hirst to use. According to Oliver Crimmen, curator of fish at the Natural History Museum, who advised Hirst on preservation, the artist should have used an alcohol-based solution for long-term protection. Though Hirst is believed to have injected the shark with formaldehyde, he is thought to have used a solution that was too weak and did not inject it deep enough for such a large fish.

Hirst will not be the first to “renew” a work of art. The eight upside-down Marcel Duchamp urinals labelled Fountain displayed in galleries around the world are all replicas made in the 1960s. The godfather of conceptualism changed art history when he exhibited the original in New York in 1917.

{ Telegraph.co.uk }

In this vast Gloucestershire flatland dotted with abandoned airplane hangars, a former Royal Air Force Station where pilots once plotted classified missions during World War II, the artist Damien Hirst (right) was overseeing a secret operation of his own one recent morning.

It was a delicate undertaking, one that required rubberized protective jumpsuits, long tables of medical equipment and more than 224 gallons of formaldehyde. The goal: to replace the decaying tiger shark that floats in one of Mr. Hirst’s best-known works of Conceptual art, “The Physical Impossibility of Death in the Mind of Someone Living.”

As rap music quietly played in the background, five men and one woman wearing bright yellow suits, black rubber gloves and breathing masks huddled over the shark’s hulking 13-foot-long replacement. The immediate impression was that the shark was being treated by a team of acupuncturists: some 200 large needles dotted its body.

So toxic was the air that the property could be reached only through security-coded iron gates, and no one, not even the artist, was allowed near the shark without protective gear. As Mr. Hirst, 41, looked on, he plucked a long hypodermic needle from a nearby worktable.

“Three different lengths of needles are being used to inject the shark with formaldehyde,’’ he said proudly, with the air of a child showing off a new toy. He flexed the syringe to demonstrate how the needles are inserted into the animal twice, each time penetrating deeper into the body cavity. “The last shark was never injected, so it decayed from the inside.’’

The original shark — a 14-footer that was caught and killed by a fisherman in Australia at Mr. Hirst’s behest in 1991 — was first unveiled to the public in its glass tank the following year at the Saatchi Gallery in London. (…) When Mr. Hirst learned of Mr. Cohen’s plans to buy the 22-ton work, he volunteered to replace the shark. “I frequently work on things after a collector has them,’’ the artist said. As it turns out, Mr. Cohen is paying for the replacement project, although he declined to say how much it would cost, other than to call the expense “inconsequential.” (The procedure involving the injection of formaldehyde alone adds up to about $100,000, including labor and materials.)

Mr. Hirst began by contacting his shark sources in Australia. And a year ago he bought the second tiger shark, this one from a fisherman who caught it just off the Queensland coast and killed it. It was shipped by sea freighter in a special 20-foot freezer with backup power, a journey that took roughly two months. Meanwhile the original tank was being renovated. (…)

Reportedly one of the richest men in Britain, Mr. Hirst can now afford to run multiple studios in London and in Gloucestershire, some two hours west of the capital, equipped with freezers full of dead animals and emergency generators in case of a power failure.

Such is his reputation that when a seven-foot shark washed up on a beach in July, and the Natural History Museum in London needed a place to store it until its staff was ready to preserve it, the first call it made was to Mr. Hirst. “They asked if I had any room in my freezer,’’ he said with satisfaction. He was happy to oblige.

Oliver Crimmen, a scientist and fish curator at the Natural History Museum in London, was in the formaldehyde pool with the shark, directing the operation.

{ NY Times | Continue reading }

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