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Bizarre Two-Headed Sharks Showing Up in Many Parts of the World
A slew of rare two-headed sharks have been found from California to the Caribbean and from Mexico to the Mediterranean, leading scientists to ponder why.
Reminiscent of the classic "Simpsons" three-eyed fish, Blinky, the mutated sharks are raising eyebrows.
A two-headed embryo of an Atlantic sawtail cat shark was found recently in the Mediterranean Sea. It was the first oviparous, or egg-laying, shark ever documented with two heads. Each head contained a mouth, two eyes and a brain, and were joined behind the gills, according to a paper published Oct. 9 in the Journal of Fish Biology. The species is considered near threatened.
Two-headed blue shark fetus discovered in the Indian Ocean off Australia.Christopher Johnston
In 2008, Christopher Johnston, a fisherman in the Indian Ocean, pulled up a pregnant blue shark. When he cut it open, a two-headed fetus popped out. Johnston tried to save it by putting it in a tank and feeding it, but it died.
Similarly, a fisherman working in the Gulf of Mexico off the Florida Keys found a fetus with two heads in a bull shark he caught. Upon examination by a scientist at Michigan State University, it was determined to be the "first recorded incidence of dicephalia in a bull shark."
Researchers from Mexico found conjoined twins in blue sharks in the Pacific Ocean and Gulf of California. Blue shark females carry many live embryos at one time, leading to these abnormalities, said the scientists.
Because these finds are so rare, it's tough to pin down a cause. Genetic or metabolic disorders, viruses, pollution or overfishing are amount the possible culprits.
Each year, 100 million sharks are slaughtered, often for their fins. Shark fin soup is a popular delicacy in Chinese and other Asian cultures. The number represents between 6.4 percent and 7.9 percent of the global shark population.
Bycatch is another factor affecting sharks in some areas. Blue sharks are among those most vulnerable. Listed as near threatened, some 20 million blue sharks are lost each year to accidental catch by longline and driftnet fisheries.
Overfishing not only puts sharks at risk of extinction, but also shrinks the gene pool, potentially causing these observed mutations.
Nicolas Ehemann, a marine scientist who found two cases of two-headed shark embryos in the Caribbean, told National Geographic that "if the two-headed fetuses are more prevalent in nature, then overfishing is a strong culprit as it may cause the gene pool to shrink."
Rare cyclops shark found off Mexico.Enrique Lucero Leon
A rare, 22-inch long one-eyed shark was found in the Gulf of California near Mexico in 2011.
And that fictional three-eyed fish from Springfield? A real three-eyed catfish was found last year swimming in the Gowanus Canal in Brooklyn. This 100-foot wide, 1.8-mile long canal was an industrial sewer from the mid-1800s and is now a U.S. Environmental Protection Agency Superfund site.
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Farms with just one or a handful of different crops encourage fewer species of pollinating and pest-controlling insects to linger, ultimately winnowing away crop yields, according to a new study.
Up to half of the detrimental impacts of the "landscape simplification" that monocropping entails come as a result of a diminished mix of ecosystem service-providing insects, a team of scientists reported Oct. 16 in the journal Science Advances.
Monocrop palm oil plantation Honduras.
SHARE Foundation / Flickr / CC BY-NC 2.0
"Our study shows that biodiversity is essential to ensure the provision of ecosystem services and to maintain a high and stable agricultural production," Matteo Dainese, the study's lead author and a biologist at Eurac Research in Bolzano, Italy, said in a statement.
It stands to reason that, with declines in the sheer numbers of insects that ferry pollen from plant to plant and keep crop-eating pests under control, these services will wane as well. But until now, it hasn't been clear how monocultures affect the number and mix of these species or how crop yields might change as a result.
Aiming to solve these questions, Dainese and his colleagues pulled together data from 89 studies cutting across a variety of landscapes, from the tropics of Asia and Africa to the higher latitudes of northern Europe. They tabulated the number of pollinating and pest-controlling insects at these sites — both the absolute number of individuals and the number of species — along with an assessment of the ecosystem services the insects provided.
In almost all of the studies they looked at, the team found that a more diverse pool of these species translated into more pollination and greater pest control. They also showed that simplified landscapes supported fewer species of service-providing insects, which ultimately led to lower crop yields.
The researchers also looked at a third measure of the makeup of insect populations — what they called "evenness." In natural ecosystems, a handful of dominant species with many more individuals typically live alongside a higher number of rarer species. The team found as landscapes became less diverse, dominant species numbers dwindled and rare species gained ground. This resulting, more equitable mix led to less pollination (though it didn't end up affecting pest control).
"Our study provides strong empirical support for the potential benefits of new pathways to sustainable agriculture that aim to reconcile the protection of biodiversity and the production of food for increasing human populations," Ingolf Steffan-Dewenter, one of the study's authors and an animal ecologist at the University of Würzburg in Germany, said in the statement.
The scientists figure that the richness of pollinator species explains around a third of the harmful impacts of less diverse landscapes, while the richness of pest-controlling species accounts for about half of the same measure. In their view, the results of their research point to the need to protect biodiversity on and around crops in an uncertain future.
"Under future conditions with ongoing global change and more frequent extreme climate events, the value of farmland biodiversity ensuring resilience against environmental disturbances will become even more important," Steffan-Dewenter said.
Reposted with permission from our media associate Mongabay.
Ivory Coast's rainforests have been decimated by cocoa production and what is left is put in peril by a new law that will remove legal protections for thousands of square miles of forests, according to The Guardian.
By Karin Kirk
Greenland had quite the summer. It rose from peaceful obscurity to global headliner as ice melted so swiftly and massively that many were left grasping for adjectives. Then, Greenland's profile was further boosted, albeit not to its delight, when President Trump expressed interest in buying it, only to be summarily dismissed by the Danish prime minister.
During that time I happened to be in East Greenland, both as an observer of the stark effects of climate change and as a witness to local dialogue about presidential real estate aspirations, polar bear migrations and Greenland's sudden emergence as a trending topic.
Heavy metals that may damage a developing brain are present in 95 percent of baby foods on the market. Cirou Frederic / PhotoAlto Agency RF Collections / Getty Images
Heavy metals that may damage a developing brain are present in 95 percent of baby foods on the market, according to new research from the advocacy organization Healthy Babies Bright Futures (HBBF), which bills itself as an alliance of scientists, nonprofit organizations and donors trying to reduce exposures to neurotoxic chemicals during the first three years of development.
By Kerstin Palme
Creepy-crawlies are among the oldest life forms on this planet. Before dinosaurs ever walked the earth, insects were certainly already there. Some estimates date their origins to 400 million years ago. They're also extremely successful. Of the 7 to 8 million species documented on Earth, around three quarters are likely bugs.
But several insect species could disappear for good in the next few decades and that would have serious consequences for humans.
Volvo introduced its first-ever all-electric vehicle this week, kicking off an ambitious plan to slash emissions and phase out solely gas-powered vehicles starting this year.
The report, released Wednesday, found that almost every European who lives in a city is exposed to unhealthy air, Reuters reported.