Om nom nom…oh, you caught me in the middle of dinner!

While conducting a survey of fish in an area of the Great Barrier Reef, scientists stumbled upon this little tableau: a tasselled wobbegong, or “carpet shark,” in the midst of devouring a brown-banded bamboo shark. (Either that, or they’re just sharing a very intense kiss.) The carpet shark, which hides in the sand and springs out at its prey, has never been photographed eating another shark before, though scientists could tell from poking around in their stomach contents that their distant cousins were sometimes on the menu. Carpet sharks seem to be slow eaters, though: the team hung around for a full 30 minutes to see if it would suck in more of the bamboo shark, but to no avail.

Maybe it just has stage fright.

Images courtesy of Tom Mannering and the journal Coral Reefs

Fresh shark fins drying on sidewalk in Hong Kong. Credit: cloneofsnake / flickr

On Friday, California governor Jerry Brown signed into law a bill outlawing the trade in shark fins, making it illegal for them to be imported, possessed, or distributed in the state. Chinese chefs were angered by the decision, since the fins are the prime ingredient in shark fin soup, a prized and expensive delicacy (although most Chinese voters in California support the ban… and so does retired NBA player Yao Ming). Other parts of shark meat are not highly valued, though, so most sharks caught are “finned” and thrown back into the ocean, where they slowly bleed to death. As many as 73 million sharks are killed each year, most for this purpose, and shark populations around the world are in serious decline—perhaps 30 percent of shark species are endangered.

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The spiny dogfish

What’s the News: Researchers found that squalamine, a steroid present in the bodies of the dogfish shark, has a protective effect against several human viruses, all of which are difficult or impossible to cure with existing drugs. The chemical has so far been shown to be relatively safe in humans and can be synthesized, suggesting it could have promise as an antiviral drug in humans.

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• Shark seek: Tiger sharks and thresher sharks remember and zero in on specific places to hunt for food in an area that might be 30 miles across. That shows they might possess not only the ability to navigate by smell or by the Earth’s magnetic field, but also broader spatial memory for their home range.
• “If you eat by shoving your entire writhing body into your meals, your dinner companions are probably going to leave.” The hagfish, however, has no such concern for manners: It absorbs its nutrients right through its skin.
• We be jammin’: Satellite provider Thuraya Telecommunications and news channel Al Jazeera both report that sources in Libya are illegally trying to jam their signals, and traced the attempts to “a Libyan intelligence service facility south of Tripoli.”
• British researchers discover a way to use urine tests to screen for prostate cancer—and potentially double the accuracy of current methods.
• Numismatist power: Coin experts create interactive digital maps of coins through history and where they came from, putting a treasure trove of information at historians’ fingertips.
• Super honey from down under: A myrtle native to Australia produces honey packed with antibacterial compounds that can stymie even antibiotic-resistant microorganisms like MRSA.

Image: Wikimedia Commons

When you’re nature’s ideal killing machine, perhaps color vision is merely an unnecessary affection. New research argues that sharks could be completely colorblind.

An Australian team led by Nathan Scott Hart investigated 17 shark species, peeking at the structure of their rod and cone photoreceptor cells in the retina. Human eyes come with red, green, and blue cone variations, allowing us to see in color. But not shark eyes. They appear to have just one kind of cone.

“Our study shows that contrast against the background, rather than color per se, may be more important for object detection by sharks,” Hart said. [CNN]

That, Hart says, may explain the common wisdom that sharks love yellow (and therefore you ought to avoid sunny swimsuits). It may be the reflective quality of yellow that catches a shark’s eye, not the hue itself.

“Bright yellow is supposed to be attractive to some sharks, presumably because it appears to the sharks as a very bright target against the water,” said Dr Hart. “So perhaps it is best to avoid those fluoro-yellow shorts next time you are in the surf.” [BBC News]

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The movie was called Jaws for a reason. The great white shark’s powerful chompers make it a feared marine killing machine. However, researchers have found, it takes a while to grow into that ferociousness—adolescent great whites don’t yet have strong enough jaws to complete an attack on tougher prey without harming themselves, and it takes until adulthood for that jaw strength to develop.

The study by Toni Ferrara and colleagues, forthcoming in the Journal of Biomechanics, used the scanning technique called computerised tomography (CT) to take a look at the great white’s developing jaw, and compare it to a relative: the sand tiger shark (also called the grey nurse shark).

With these scans, they were able to create digital three-dimensional models of the sharks’ heads. The models revealed that the great white’s jaws are reinforced by layers of tough “mineralised cartilage”, which take years form. So until the sharks grow to approximately 3m [10 feet] long, they are unable to gouge chunks out of larger, tougher prey, such as sea mammals. [BBC News]

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From Ed Yong:

When Chrysoula Gubili from the University of Aberdeen compared the DNA of white sharks from around the world, she found a big surprise. The great white is the most genetically diverse shark studied so far but the Mediterranean fish are only distantly related to nearby populations in the North-West Atlantic, or even in South Africa. Their closest kin actually live half a world away in the Indo-Pacific waters of Australia and New Zealand….

Gubili thinks that the European population was set up by a single founding female who got lost. Female great whites undergo long migrations of thousands of kilometres, but they tend to return to the place where they were born. However, it’s possible that some individuals lose the bearings on these monster treks. These navigational problems rarely amount to anything. But if the wayward female is pregnant, she might end up setting up an entirely new splinter group in a far-off corner of the world.

Read the rest of this post at DISCOVER blog Not Exactly Rocket Science.

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Image: flickr / hermanusbackpackers

80beats aims to bring you all the science news that’s fit to turn into bytes of digital information, but sometimes DISCOVER’s other bloggers get to the juicy news stories first. To make sure you don’t miss anything, here are a couple of links:

• Supersenses! Ed Yong at Not Exactly Rocket Science covers two journal articles in which scientists investigated the amazing sense of touch in seal whiskers and sharks’ equally astounding sense of smell in the water. To test the sensitivity of seal whiskers, researchers blindfolded a seal and had him “read” the turbulence of a wake.

• For the first time, scientists get to watch as an exoplanet orbits its star—63 light years away. Check out Phil Plait’s Bad Astronomy post for the must-see image. Elsewhere on the Web, National Geographic notes that this planet, Beta Pictoris b, is just a baby. According to the paper published in Science, Beta Pictoris appears to be only a few million years old, yet it’s fully formed–which surprised astronomers who thought that planets take much longer to come into their own.

• Finally, a look back to the marine reptiles that ruled the prehistoric seas. A new study suggests that unlike most reptiles, these mighty sea monsters may have been able to regulate their body temperatures, reports Ed Yong. That ability could have allowed these top-of-the-food-chain hunters to swim fast and dive deep, regardless of ocean temperatures.

Call it the green Nobels: Tonight in the San Francisco Opera House, six people will each receive a $150,000 Goldman Environmental Prize for their efforts to protect sharks and elephants, to promote sustainable agriculture, and to fight for other green causes.

The awards go out by region. Here in North America, the winner was Michigan’s Lynn Henning, a self-described “redneck from Michigan” who investigated huge factory farms there. Henning, 52, began testing water herself to track discharges from the farms into local waters. She has been threatened and sued and had dead animals dumped on her porch. But her tireless detective work has contributed to the state closing one factory farm and fining others more than $400,000 for 1,077 violations since 2000 [Detroit Free Press]. As Michigan’s Department of Environmental Quality suffered staff cuts, Henning’s determination kept regulators focused, former department head Steve Chester says.

South and Central America’s winner, Randall Arauz of Costa Rica, turned his attention to stopping the wasteful practice of shark finning. Arauz used a secretly recorded video to expose a ship illegally landing 30 tons of shark fins, which led to the death of an estimated 30,000 sharks. The video caused outrage in Costa Rica, which Arauz used to mobilize opposition [San Francisco Chronicle]. The Costa Rican government banned the practice, and its rules are now the model for those trying to work up international agreements against shark finning. (Worldwide restrictions were just shot down at the Convention on International Trade in Endangered Species.)

The other winners:

In Europe, Malgorzata Gorska of Poland, who stopped a highway project that would have cut through a forest.

In Asia, Sereivathana Tuy of Cambodia, who taught farmers how to ward of wandering Asian elephants rather than kill them.

In Africa, Thuli Brilliance Makama of Swaziland. This environmental lawyer won a fight for local residents to have more say in environmental decisions by the government, especially those regarding the expansions of game parks that would force people off the land.

And for island nations, Cuban Humberto Rios Labrada, who pushed for more crop diversity and less pesticide use in Cuban agriculture.

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Image: NASA

In a victory for East Asian nations that consume sharkfin soup, the Convention on International Trade in Endangered Species (CITES) has shot down three of four proposals to protect sharks. Member nations of CITES who gathered in Doha, Qatar, rejected proposals that would have required countries to strictly regulate — but not ban — trade in several species of scalloped hammerhead, oceanic whitetip and spiny dogfish sharks [The New York Times]. Japan also lobbied against the protections, because it strongly opposes extending the convention’s protections to any marine species (including the bluefin tuna that is so beloved by Japan’s sushi connoisseurs).

The only proposal that managed to get through was a proposal from the European Union and the island nation of Palau to protect the porbeagle shark, which is prized for its meat. But even this victory is a shallow one, as the proposal passed by a margin of just one vote, and could be overturned at the conference’s final session on Thursday.

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DISCOVER has covered scientists using DNA to investigate ivory smuggling in Africa and whether that’s endangered bluefin tuna in your sushi in New York City. Now an American team is using to that tactic to get on the trail of another questionable animal market, the sharks killed to make shark fin soup in Asia. The study appears in Endangered Species Research.

For the first time, scientists have used DNA from shark fins to determine where they came from. The researchers traced finds from the scalloped hammerhead shark species—collected at the world’s biggest fin market in Hong Kong—back to rare populations in the Atlantic and Indo-Pacific oceans [National Geographic News]. According to their analysis of the mitochondrial DNA, which they compared samples from live hammerhead population, 21 percent of the Hong Kong fins came from water off places like the United States, Belize, and Panama where the sharks are classified as endangered.

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Sharks and humans seem more and more alike with each new scientific find. Not only do some sharks have hunting patterns that resemble those of serial killers, but now scientists have discovered that the hammerhead shark’s distinctive head shape allows it to see like a human.

Binocular vision occurs when the fields of two eyes overlap, allowing the accurate perception of depth and distance. It is especially important for predators which need to judge the distance to their prey [BBC News]. Researcher Stephen Kajiura, a sensory biologist, suggests that the stereo vision helps the sharks hunt prey like squid that dart around in three dimensions. The wide set eyes also allow the sharks to see through 360 degrees of vision, according to the researchers, who published their findings in The Journal of Experimental Biology.

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Great white sharks, much like humans, tend to stick to familiar turf, according to new research. Also like a lot of people, they like to hang out along the coastal waters of California. Sharks tagged with acoustic devices often spent up to 107 days at four key sites along the central and northern California coast where seals and sea lions are abundant: Southeast Farallon Island, Tomales Point, Año Nuevo Island and Point Reyes [LiveScience]. A few of the fearsome predators were tracked as far inland as the Golden Gate Bridge, apparently in search of snacks, say the researchers. The study, the largest and most detailed study of North American great white sharks, provides evidence contrary to the popular notion of great white sharks swimming aimlessly in the ocean.

The sharks under study divided most of their time between three locations: Northern California, Hawaii, and an area that the researchers called the white shark café, a spot in the open ocean about halfway between the Baja Peninsula and the Hawaiian Islands. Exactly what goes on at the café is still unknown–although researchers suspect it may be a hot spot for mating. Lead researcher Salvador Jorgensen explains that male white sharks “converge in a very specific area of the cafe,” Jorgensen said, while female sharks move in and out of the area. “It adds a little more evidence to the argument that this could be an important reproductive area” [Washington Post].

The scientists tracked the snaggly toothed predators between 2000 and 2008 from the Bay Area to San Diego, Hawaii and back as the sharks followed a route that was carried out with surprising precision and under a strict time frame [San Francisco Chronicle]. These great whites have been isolated from other great white sharks near Australia and South Africa for so long that they are now genetically distinct. The study was published in the journal Proceedings of the Royal Society B.

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Image: flickr / hermanusbackpackers

The tiny island nation of Palau has taken a big step to protect the ocean’s endangered sharks, by designating all of its territorial waters a shark sanctuary within which all commercial shark fishing is prohibited. Palau’s president, Johnson Toriboing, announced the plan at a meeting of the UN General Assembly last Friday. Sharks are increasingly under threat as the demand for shark-fin soup—a delicacy in many Asian countries—has risen worldwide. “The need to save the ocean and save sharks far outweighs the need to enjoy bowls of soup,” Toriboing said [National Geographic News].

Palau consists of about 200 small islands in the Pacific Ocean to the east of the Philippines; its expansive marine territory spans 230,000 square miles, an area about the size of Texas. About 130 species of rare sharks either make their homes or pass through these waters, including hammerheads, leopard sharks, and reef sharks, as well as the related stingrays.

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Extinction threatens four more species of deep-sea sharks and rays than a year ago, bringing the total species classified as “threatened” to 20 species, or nearly a third of the world’s 64 species, according to a report (pdf) released today by the International Union for Conservation of Nature. Rays and sharks are already two of the most endangered fish groups, researchers say.

The threat facing pelagic sharks and rays stems largely from overfishing; in many parts of the world, shark meat is considered a delicacy, and some animals  become ensnared in fishing nets intended to catch tuna or swordfish. The report also urges governments to halt shark “finning,” the slicing of fins from captured sharks which are then tipped back into the sea to die, which it says is a growing industry providing ingredients for the Asian delicacy, shark fin soup. Although finning bans have been declared in most global waters, little effort is made to enforce them, said the IUCN [Reuters].

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