Ancient reptile with ‘ridiculously long neck’ unearthed in Alaska

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The long-necked elasmosaur as imagined by Anchorage-based artist James Havens, who is working with Druckenmiller to realistically interpret ancient life forms. (James Havens, courtesy of UAF)

The fossilized remains of an ancient marine reptile with an extremely long neck and paddlelike appendages were recently uncovered in an unlikely place: the side of a cliff in Alaska.

The bones belong to an elasmosaur, an animal that swam the seas about 75 million years ago during the Late Cretaceous period, said Patrick Druckenmiller, earth sciences curator at the University of Alaska Museum of the North. It’s the first time that the skeleton of one of these creatures has been found in the state, he added.

“This is a very unusual group of marine reptiles that belongs to a larger group known as plesiosaurs, Druckenmiller told Live Science. “Elasmosaurs are famous because they have these ridiculously long necks and relatively small skulls.” [Image Gallery: Ancient Monsters of the Sea]

Most of the newly uncovered elasmosaur’s bones are still lodged in a rocky cliff in the Talkeetna Mountains of southern Alaska, so no one has measured the full skeleton yet. But Druckenmiller, who visited the fossil site in June, estimates that the animal was about 25 feet long, with a neck that made up half its body length.

The incredible length of the ancient carnivore’s neck gave rise to an interesting theory in the 1930s, when someone suggested that the mythical Loch Ness monster was really just a plesiosaur (possibly an elasmosaur) that didn’t go extinct with the rest of its species. But Druckenmiller said that theory is a “bunch of bunk,” because there’s no way a plesiosaur could have held its head up out of the water like a swan (which is how “Nessie” commonly appears in popular culture and hoax photographs).

It is true, however, that plesiosaurs can sometimes end up in unusual places. The newly discovered Alaskan elasmosaur was found amid a mountain range that boasts peaks that are nearly 9,000 feet high. That’s a long way from the seafloor, which is where the remains of any elasmosaur would have likely settled after it died. So how did the bones find their way up the mountain?

“The rocks that the skeleton was found in were laid down on the seabed about 70 to 75 million years ago. At that time there was a sea along the southern margin of [what is now] Alaska,” said Druckenmiller, who added that over the course of many millions of years, tectonic activity under that ancient sea caused the seafloor to rise up thousands of feet.

The rocky cliffs of the Talkeetna Mountains boast many fossils that hint at this aquatic past. However, most of the fossils found there belong to invertebrates, not marine vertebrates, Druckenmiller said. The fossilized remains most commonly found in the range belong to ammonites, an extinct group of marine animals that he said look like “overgrown nautilus” (mollusks with hard, spiral shells).

Finding the remains of a vertebrate, especially one as large and intact as the elasmosaur, is a real treat for Druckenmiller, who noted that similar fossils have been found in Canada and in the continental United States, but only in places like Kansas, the Dakotas and Montana, where rocky, barren terrain is better-suited for fossil hunting. (The presence of marine animal fossils in those states has to do with the fact that, millions of years ago, central North America was submerged under a seaway that divided the continent into two landmasses.)

“These fossils are found in classic ‘Badlands’ environments in other parts of the world, with nice outcroppings of rock sticking out everywhere,” Druckenmiller said. “In Alaska, there’s a lot of vegetation, so it’s hard to find good, accessible rock. Where we usually find it is pretty remote, mountainous areas where there’s not a lot of vegetation because of the high elevation and the steep slopes.”

And the vertical slopes of the soaring Talkeetna Mountains make the region a better place than many others in southern Alaska to look for fossils. It’s not the first time an ancient skeleton has been discovered there. In 1994, workers digging a quarry in the Talkeetna range unearthed the partial remains of a plant-eating ornithopod dinosaur (a close relative of duck-billed dinosaurs) that had floated out to sea and finally came to rest on the seabed, which later rose up to form the massive mountains.

That hadrosaur, nicknamed “Lizzie,” is on display at the Museum of the North (where Druckenmiller works) in Fairbanks, Alaska. It’s not yet clear where the elasmosaur skeleton will end up once it’s completely unearthed, but Druckenmiller said he’s glad the ancient remains are close enough to visit.

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Armored spiky worm had 30 legs, will haunt your nightmares

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An illustration showing the many legs and spikes covering the early Cambrian creature, Collinsium ciliosum. (Javier Ortega-Hernández)

A spiky, wormlike creature with 30 legs — 18 clawed rear legs and 12 featherlike front legs that likely helped it filter food from the water — once lived in the ancient oceans of the early Cambrian period, about 518 million years ago, a new study finds.

The critter is one of the first known animals on Earth to develop protective armor and to sport specialized limbs that likely helped it catch food, the researchers said. This newfound species lived during the Cambrian explosion, a time of rapid evolutionary development, they said.

“It’s a bit of a large animal for this time period,” said one of the study’s lead researchers, Javier Ortega-Hernández, a research fellow in paleobiology at the University of Cambridge. “The largest specimen is just under 10 centimeters [4 inches], which, for a wormy thing, is quite mighty.” [See Images of the Spiky Worm & Other Cambrian Creatures]

The creature likely used its rear clawed legs to anchor to sponges or other penetrable surfaces, and waved its feathery front limbs to and fro in the current to catch nutrients in the water, Ortega-Hernández said. This technique is still used by modern animals, such as bamboo shrimp, that capture passing meals with their fanlike forearms.

But, because the Cambrian critters were “soft and squishy,” it’s likely they waved their limbs in a gentle motion, Ortega-Hernández told Live Science. “I don’t imagine they would have quick muscle control.”

A squishy creature that didn’t move quickly needed a steadfast defense strategy, and that’s likely why it had so many spikes, he said. Other Cambrian wormlike creatures, such as the bizarre Hallucigenia, also sported spines.

Hallucigenia has two sets of spines per leg,” Ortega-Hernández said. “This one has up to five, which means it was a much more heavily armored creature.”

Collins’ monster

Researchers have dubbed the new creature Collinsium ciliosum, or Hairy Collins’ Monster, named after Desmond Collins, a paleontologist who discovered a fossil of a similar Cambrian wormlike creature in Canada in the 1980s. Since then, researchers have found five species of Collins’ Monster (in the family Luolishania), including one from Australia.

But, unlike earlier fossils, the newfound specimens offer researchers a spectacular view of the prehistoric creature. One fossil displays much ofCollinsium ciliosum’s body, including its digestive tract and even the delicate, featherlike structures on its front limbs. Based on the fossils, when it was alive, the worm likely didn’t have any eyes or teeth, Ortega-Hernández said.

Over the past three years, scientists at Yunnan University in China and the University of Cambridge have uncovered and studied 29 C. ciliosum fossils from the early Cambrian Xiaoshiba biota, adeposit in southern China that contains a rich collection of fossilized Cambrian creatures, he said.

An analysis of C. ciliosum’s anatomy indicates it’s a distant ancestor of modern-day velvet worms, also known as onychophorans — a small group (just 180 species) of squishy worms that live in tropical forests, shoot slime at their prey and resemble legged worms.

Interestingly, the Collins’ Monsters were likely a more diverse group that “came in a surprising variety of bizarre shapes and sizes” than today’s onychophorans, Ortega-Hernández said in a statement.

This isn’t the first time that an ancestral group has displayed more diversity than its modern-day relatives. Sea lilies (crinoids) and lamp shells (brachiopods) also follow this trend. But Collins’ Monsters are the first example of this evolutionary pattern playing out in a mostly soft-bodied group, the researchers said. [See Images of Another Bizarre Cambrian Creature]

The study is “a superb description based on absolutely exquisite fossils,” said Greg Edgecombe, a researcher of arthropod evolution at the Natural History Museum in London, who was not involved in the new study.

The new finding drives home that Cambrian wormlike animals such asHallucigenia and the new Collinsium are the ancestors of Onychophora, Edgecombe said.

“That means they are more closely related to Onychophora than to any other living groups (such as arthropods or tardigrades),” Edgecombe told Live Science in an email. “Rather than floating around on the tree of life without an exact home,” these creatures can be pinpointed to a living group, Edgecombe said.

The findings were published online June 29 in the journal Proceedings of the National Academy of Sciences.

 

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New jelly-bean-size ‘masked’ frog discovered in the Andes

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N. madreselva’s distinctive markings include a dark brown “face mask.” (Vanessa Uscapi)

A tiny new frog species discovered in the Peruvian Andes has a white-mottled belly and a dark face mask that makes it look like a bandit.

Noblella madreselva lives in the humid cloud forest near Cusco, Peru, probably only in the valleys right around where it was discovered, researchers report Aug. 6 in the journal ZooKeys. The frogs, which are not much bigger than jelly beans, can fit on the tip of a human finger. They’re active during the day, and live in leaf litter on the forest floor.

Vanessa Uscapi, a biologist at the National University of Saint Anthony the Abbot in Cusco, Peru, discovered the new tiny frog in January 2011, but only now has it been officially described. She and her colleagues picked the name madreselva to honor conservation initiatives in the region: The word means “mother jungle” and is also the name of a nearby ecotourism lodge and a small valley where a group called Sircadia is trying to launch a sustainable eco-community. [In Photos: Teeny-Tiny Frogs Found in Brazil]

N. madreselva has a dark-brown body with a darker patch on its head. Its belly is decorated with striking white marks. It’s not the only recently discovered tiny frog with bold coloration; in June, researchers in Brazil announced the discovery of seven itsy-bitsy new frogs from rainforests in Brazil. Those frogs, all of which belong to the genus Brachycephalus, came in colors ranging from greenish-brown to bright orange and blue.

The smallest frog ever discovered hails from Papua New Guinea, and could perch quite comfortably on a penny. Frogs, of the genus Paedophryne, are less than half an inch long. The smallest species in the genus, Paedophryne amauensis, grows to be just 0.3 inches, on average. It’s not only the world’s smallest frog, but also the smallest vertebrate discovered so far.

The newly discovered Peruvian frog likely has a very limited geographical range, making it vulnerable to the effects of deforestation and habitat loss, Uscapi and her colleagues said. Andean frogs are also at risk of a deadly chytrid funguscalled Batrachochytrium dendrobatidis. This fungus has devastated frog populations worldwide. It causes the amphibians’ skin to harden, disrupting their electrolyte balance and causing cardiac arrest. A December 2013 study in the journal Conservation Biology found that climate change in the Andes is increasing the area in which this fungus can thrive. Alessandro Catenazzi, one of the researchers on the team that discovered the new frog along with Uscapi, was an author of that 2013 study as well.

The researchers found that highlands frogs in the Andes were vulnerable to the fungus, while lowlands frogs were likely to suffer not from the fungus, but from warming temperatures.

“The frogs in the highlands will not suffer from climate change anytime soon, but they’re doomed because of the fungus, whereas the frogs in the lowlands are shielded from the fungus but they’re going to be toasted because it’s too hot,” Catenazzi told Live Science at the time.

 

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Alien of the deep has needle-sharp teeth and a shiny head lure

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A female of the newfound Lasiognathus dinema species from the Gulf of Mexico. (Theodore Pietsch, Ph.D. University of Washington)

Lurking in the dark depths of the sea, a new species that looks more like an alien than a fish has been discovered, a creature with needlelike teeth and a glowing fishing pole of sorts atop its head.

Scientists spotted three females of the new species of anglerfish between 3,280 feet and nearly 5,000 feet beneath the Gulf of Mexico. The little fish, whose bodies ranged in length from 1.2 to 3.7 inches, live under extreme conditions: No sunlight penetrates their deep habitats where they endure immense pressures of more than 2,200 pounds per square inch.

Now called Lasiognathus dinema, the anglerfish stood out from other species in its genus by the curved appendages jutting out from its so-called esca, or the organ at the tip of the “fishing rod” that contains light-producing bacteria. The species name dinema comes from the Greek words “di” for “two” and “nema” for “thread,” referring to the threadlike extensions sprouting from the bases of the light organ’s hooks, the researchers, Tracey Sutton of Nova Southeastern University in Florida and Theodore Pietsch of the University of Washington, write in the journal Copeia (published by the American Society of Ichthyologists and Herpetologists). [See Photos of a Creepy, Deep-Sea Anglerfish]

Anglerfish use this lure to reel in unsuspecting fish that mistake the light for a meal.

The researchers aren’t sure whether or not Lasiognathus dinema can move its head rod at will, but it seems likely. “This particular group of anglerfishes has never been seen alive, but based on the musculature and anatomy, it looks like they have a great deal of control over the ‘fishing rod,'” Sutton told Live Science.

The researchers found just females of this species but suspect the males would be smaller, as other anglerfish in the suborder Ceratioidei show extreme sexual dimorphism — females of the species Ceratias holboelli, for instance, can be some 60 times longer and a half million times heavier than the males.

The males in this group also often lack any lure and some fuse themselves to the female, living off of nutrients from her bloodstream, providing sperm to fertilize her eggs in return.

“So far, we do not have any female specimens with males, but there are so few specimens of this group that are known, the best answer would be, ‘We don’t know if the males attach themselves in this genus,'” Sutton said.

Like the newfound creature, most anglerfish are relatively small beasties — malePhotocorynus spiniceps may be the world’s smallest vertebrate — but Sutton has seen one off Iceland spanning nearly 3 feet, he said.

The team found the haunting new species while out on the Gulf as part of the Natural Resource Damage Assessment Process conducted by the National Oceanic and Atmospheric Administration. Lasiognathus dinema was found near the Macondo wellhead at depths where intrusions of hydrocarbons from the BP oil spill in 2010 were reported.

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Dementor’ wasp turns cockroaches into zombies

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It’s the stuff of nightmares – a newly-discovered wasp that turns cockroaches into zombies.

The Ampulex Dementor, named after the terrifying soul-suckers from the “Harry Potter” movies, is one of a 139 new species discovered in Asia’s Mekong Delta in 2014, according to a World Widlife Fund report.

The wasp, which was discovered in Thailand, injects venom into a mass of neurons on the cockroach’s belly that turns the roach into a passive zombie, according to the report. “Cockroach wasp venom blocks receptors of the neurotransmitter octopamine, which is involved in the initiation of spontaneous movement. With this blocked, the cockroach is still capable of movement, but is unable to direct its own body,” the report explained.

It gets worse for the wasp’s unfortunate victim. “Once the cockroach has lost control, the wasp drags its stupefied prey by the antennae to a safe shelter to devour it,” the report added.

Visitors to the Museum für Naturkunde in Berlin voted to name the waspAmpulex Dementor in a poll, noting the insect’s similarity to the dementors that terrorize Harry Potter and his fellow wizards.

The species was discovered by Michael Ohl, Volker Lohrmann, Laura Breitkreuz, Lukas Kirschey, and Stefanie Krause.

The opportunity to name a fascinating new species strengthens such as the Ampulex Dementor helps build public awareness of conservation issues, experts say. “I am convinced that events like this increase people’s curiosity about local and global fauna and nature,” said Ohl, one of the Museum für Naturkunde researchers who led the naming process.

Other new species detailed in the report include Phryganistria Heusii Yentuensis, the world’s second-longest insect, at 21 inches, which was discovered in Vietnam. Researchers also found the Gracixalus Lumarius, a color-changing thorny frog, in Vietnam.

The 139 new species include 90 plants, 23 reptiles, 16 amphibians, nine fish, and one mammal,

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Oldest panda in captivity celebrates 37th birthday

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Jia Jia, born in 1978, was officially recognized on July 28, 2015 as “Oldest panda ever in captivity” and “Oldest panda living in captivity” by Guinness World Records (New China TV)

A female panda in Hong Kong celebrated her 37th birthday today (July 28), becoming the oldest panda in captivity, and setting two new Guinness World Records in the process.

The giant panda, named Jia Jia, now holds the title for “oldest panda ever in captivity” and “oldest panda living in captivity.” The panda’s advanced age is equivalent to 111 human years, according to officials at the Guinness World Records organization.

Jia Jia lives with the world’s second-oldest panda, An An, who is approaching his 29th birthday, at Ocean Park, an animal and amusement park in Hong Kong. [Cute Alert! Adorable Photos of Giant Panda Triplets]

“Giant pandas are undoubtedly one of the Earth’s most endangered and well-known species. Thanks to the attentive care of the Park for the past 16 years, Jia Jia has set a new longevity record,” Blythe Fitzwiliam, an adjudicator at Guinness World Records, said in a statement.

The previous oldest panda in captivity was Dudu, who was born in 1962 and lived to be 36 years old. Before she died, Dudu spent most of her life at the Wuhan Zoo in Chengdu, China.

 

Jia Jia, An An and two other giant pandas (Ying Ying and Le Le) celebrated the new Guinness World Records accomplishment with an icy birthday cake and partied with 200 local senior citizens and their caregivers, who were invited to the celebration by park officials.

Jia Jia and An An arrived in Hong Kong as a gift from the China Central Government in 1999, to mark the semi-autonomous city’s handover by Britain two years earlier. Almost 27 million visitors have come to see the pandas since their arrival, according to Ocean Park officials. Both Jia Jia and the previous record holder, Dudu, were rescued from the wild.

Wild pandas used to roam all over southern and eastern China, even venturing into Myanmar and Vietnam, but are now considered one of the world’s most endangered animals. However, in the past decade, the population of giant pandas in the wild has increased by 17 percent, according to the World Wildlife Fund (WWF). The latest 2014 census counted 1,864 giant pandas living in the wild.

Jia Jia’s longevity is especially notable because the average lifespan for giant pandas is typically 14 to 20 years in the wild, and 30 years in captivity, according to WWF.

“Given their advanced years, An An and Jia Jia are both in satisfactory health,” Suzanne Gendron, executive director of zoological operations and education at Ocean Park, said in a statement. “Jia Jia takes regular medication for various conditions such as high blood pressure and arthritic pain, whereas An An has high blood pressure, which is common for giant pandas around his age.”

An An’s blood pressure is controlled with medication, though Jia Jia can’t do much to remedy the deterioration of her eyesight, which is caused by cataracts, park officials said. Still, she can recognize the voices of her caretakers, some of whom she has known for 15 years. “This gives her a strong sense of security,” Gendron said.

“It gives us tremendous pride that Hong Kong Ocean Park is now the home of the world’s oldest ever giant panda and the world’s second-oldest male giant panda under human care,” Leo Kung, chairman of Ocean Park, said in a statement. “A lot of credit goes to our dedicated animal-care team, which has continued to benefit from the advice and guidance of experts in Sichuan through their regular visits to the Park.”

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One tough bite: T. rex’s teeth had secret weapon

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An illustration of a Gorgosaurus using its serrated teeth to rip apart its meal, a young Corythosaurus in Alberta, 75 million years ago. (Painting by Danielle Dufault)

Secret structures hidden within the serrated teeth of Tyrannosaurus rex and other theropods helped the fearsome dinosaurs tear apart their prey without chipping their pearly whites, a new study finds.

Researchers looked at the teeth of theropods — a group of bipedal, largely carnivorous dinosaurs that includes T. rex and Velociraptor — to study the mysterious structures that looked like cracks within each tooth.

The investigation showed that these structures weren’t cracks at all, but deep folds within the tooth that strengthened each individual serration and helped prevent breakage when the dinosaur pierced through its prey, said study lead researcher Kirstin Brink, a postdoctoral researcher of biology at the University of Toronto Mississauga. [Image Gallery: The Life of T. Rex]

The new study upends one from the early 1990s, Brink said. Researchers first noticed these cryptic cracks on the tooth of a T. rex cousin named Albertosaurusabout two decades ago.

Initially, the researchers thought the cracks were signs of damage, likely acquired when the dinosaur ate a hearty meal. But the new analysis finds that isn’t the case, Brink said.

“I sectioned teeth from eight other theropods besides Albertosaurus, and found that the structure is actually in all theropods, and it’s not actually a crack,” she told Live Science.

Serrated teeth

The study actually began with a Dimetrodon, a Paleozoic animal with serrated teeth that lived before the time of the dinosaurs. When Brink sliced theDimetrodon tooth in half and compared it with the serrated teeth of dinosaurs, she found they had different internal structures.

“They look very similar on the outside,” Brink said. “It’s only when you cut them open [that you see] that they’re completely different.”

Curious, she obtained two to three teeth from eight different theropods species, including T. rex, Coelophysis bauri and Carcharodontosaurus saharicus. She also looked at specimens of theropod teeth that had not yet fully matured and erupted past the gum line, meaning, “they had not been used for feeding,” Brink said.

An analysis using a scanning electron microscope and a synchrotron (a microscope that helps determine the chemical composition of a substance) showed that each tooth, even the ones that had not yet erupted, had these cracklike structures next to each serration, she said. This debunked the idea that the cracks were artifacts of eating a meaty meal, she said.

Furthermore, each structure has a few extra layers of calcified tissue, called dentine, under the tooth’s outer enamel coating, making it tough and hard.

“We proposed a developmental hypothesis that these are structures created when the tooth is first forming,” Brink said. “It actually helps to deepen the serration within the tooth and strengthen each serration and the tooth overall.”

Serrated teeth help animals pierce through flesh and hold onto chunks of meat. The formations, which the researchers call “deep interdental folds,” strengthen the serrations. In fact, they likely helped theropods survive as top predators for about 165 million years, Brink said.

Serrated teeth still exist today in Komodo dragons. However, Komodo dragon teeth don’t have deep interdental folds, nor do they have the extra layers of dentine that would strengthen their bite, Brink added.

She called the toothy finding fascinating and “unexpected.”

“It’s really cool that such a small, little change in the tooth structure, a small arrangement of the dental tissues, could completely change the ways these animals are living,” she said.

The study was published online today (July 28) in the journal Scientific Reports.

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Tourists get rare chance to pet gray whale and her calf

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A whale of a time in Baja California, Mexico. (YouTube/Barcroft TV)

A group of lucky tourists had a whale of a time on recent cruise through the San Ignacio Lagoon in the Mexican province of Baja California.

Wildlife photographer Mark Carwardine captured images of a gray whale and her calf swimming up to a small boat full of tourists and allowing the humans to pet them.

The gray whale population of the Pacific, which is made up of a meager 150 whales, is listed as critically endangered by the International Union for Conservation of Nature, making this encounter extremely rare.

Despite their foreboding size, gray whales are known for being quite friendly.

“Locals here affectionately call gray whales “friendly ones” as they have an unusual tendency to approach whale-watching boats and check out the occupants,” writes the World Wildlife Federation.

Footage of the experience was also captured by drone that showed the enormous size of the these gentle giants compared to the small boat.

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North Carolina beachgoers craft homemade shark cages

Desperate times call for desperate measures, right?

Amid the uptick in headline-making shark attacks, one couple in North Carolina tried to protect themselves against a possible attack by crafting a bizarre-looking contraption to ward off any relatives of Jaws.

While enjoying a sunny day at the Outer Banks, Jordan Cutrell captured a video of Sandi and Scott Bergman entering the ocean with what appeared to homemade shark cages.

“These people are going swimming in their shark proof cages,” a voice narrates at the top of the video. “They don’t wanna get bit.”

The Bergmans made it waist-deep into the water before a lifeguard comes running to the shore, blowing his whistle. Despite the local stir they caused, the beachgoers say their cages, which they constructed from plastic and PVC piping, were just meant as a light-hearted joke.

 

“We went out there with the intention of filming a spoof about this guy who comes up with something called Block Jaw. It’s your own personal shark cage,” Sandi  Bergman told WRIC Richmond. “It (was) very crowded; it’s July, and as soon as we set up immediately people started to watch us.”

As of Wednesday morning, Cutrell’s video had already hit over 250,000 views on YouTube so the Bergmans were clearly on to something.

It comes as vacationers are increasingly wary of getting in the water in the mid-Atlantic region.  In July, a man swimming about 30 feet from the shore along Ocracoke in the Outer Banks was bitten by a shark— which was the seventh attack in three weeks.

“The reactions are all over the place,” said Bergman. “Some people are saying ‘these people are idiots- how could they think that would protect them in any way?’ Others say, It’s great, I love it, I want one.”

 

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High temperatures make some lizards change sexes

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 (Arthur Georges)

When some lizards can’t take the heat, they change sexes. In a recent studypublished in Nature, researchers in Australia revealed that rising temperatures are causing male Australian Bearded Dragons to change into females when developing in the egg. Not only that, but they make better mothers, laying more eggs than naturally born females.

Prior to this discovery, it was believed that some reptiles, such as crocodiles and certain types of lizards and turtles have temperature-dependant sex determination (TSD), while others, like some lizards and turtles, and all snakes, have genotypic sex determination (GSD).

“TSD species were thought to be particularly vulnerable to climate change and GSD species secure,” study co-author Arthur Georges of the University of Canberra told Foxnews.com. “I suppose what our work means is that, firstly, TSD and GSD are not that far apart mechanistically or in evolutionary terms, which is contrary to mainstream thinking. Secondly, it means that even GSD species can be vulnerable to climate change because higher temperatures can make them switch to TSD.”

Bearded dragons typically inherit two sex chromosomes — ZZ for the males and ZW for the females. After bringing in 131 specimens from the wild, George and Dr. Clare Holleley conducted controlled breeding experiments using a variety of cutting edge techniques, including comparative genome hybridization to demonstrate sex reversal. They also used a bacterial artificial chromosome (BAC) library.

“We used a bacterial artificial chromosome library to generate and verify sex specific sequence and probes that were important to determine the underlying sex of individuals,” Georges said. “A BAC library is constructed by cutting up the dragon DNA, the whole genome, and inserting the fragments into bacterial colonies, one fragment per colony, so you can pull particular dragon sequence out at will.”

Georges added that the team then performed a series of incubation experiments in the laboratory, examining the specimens caught in the wild to show that the underlying genotype of some dragons (ZZ) was discordant with their actual sex (female). In other words, they were able to show that 11 lizards with male chromosomes had changed into fertile females during incubation.

How the heat causes the dragons’ chromosomes to change remains a mystery, though Georges added that he has a theory.

“We believe that after the master sex gene on the sex chromosomes does its work, a cascade of gene regulatory processes (those governing development) is initiated leading to a male or a female hatchling reptile,” Georges said. “For the most part, these regulatory processes are buffered in some way from varying temperatures in the nest, but only to a point. At high temperatures, the control of the master sex genes is eroded, and temperature brings in its influence.”

It will be difficult to demonstrate exactly how this is done, he suggested.

It was also found that temperature alone determined the chromosomes of the sex-changing dragons’ offspring, revealing that the W chromosome was completely gone in one generation. Normally, the missing female chromosome would mean disaster for a species, all but ensuring its demise. This isn’t the case with Australian bearded dragons.

“The dragon is saved from such a fate because temperature takes over the role of producing the requisite females for future generations,” Georges explained. “After the W chromosome is lost, males are produced at low temperatures from ZZ animals, and females are produced at high temperatures from ZZ animals. So all is well, so long as temperatures do not rise to the point where all ZZ animals are reversed.”

It is unknown why the sex-changed females produce more eggs than the naturally born females, but Georges suggested it has something to do with degenerating chromosomes.

“It could be that the genes associated with sex characteristics accumulate on the sex chromosomes, and given that the W chromosome, like the Y chromosome in mammals, tends to be a degenerate copy of the Z (or X in mammals), then females with two Z chromosomes are better than normal females with one Z and one (degenerating) W chromosome,” he said. “[It’s] a matter for speculation at present, but fodder for further experimentation.”

The study was carried out by the Institute for Applied Ecology, University of Canberra, and the School of Life Science, La Trobe University, Melbourne, and can be found in the online journal Nature.

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