First known venomous frogs stab with toxin-dripping lip spikes

Carlos Jared discovered the first known venomous frog by accident. And it took him a long time to connect his pain with tree frogs that head-butted his hand.

Jared, now at the Butantan Institute in São Paulo, got his first hint of true venom when collecting yellow-skinned frogs (Corythomantis greeningi) among cacti and scrubby trees in Brazil’s dry Caatinga region. For hours after grabbing the frogs, intense pain radiated up his arm for no obvious reason.
He knew frogs have no fangs to deliver toxin. Many frog species can poison an animal that touches them, but they’re poisonous. True venomous animals actively deliver toxins.

Jared realized head-butting delivers venom only when he saw the frogs’ upper lips under a microscope. Bone spikes erupted near venom glands that looked “giant,” he says. As a frog’s lips curl back, glands dribble toxins onto spikes sticking out from the skull and the frog pokes them against foes.

Gram for gram, the frog venom is almost twice as dangerous to mammals as typical venom of the feared Bothrops pit vipers, Jared, Edmund Brodie Jr. of Utah State University in Logan and their colleagues report online August 6 in Current Biology.
The researchers also report a second spiky-skulled venomous frog, Aparasphenodon brunoi, which is a forest species not very closely related to yellow-skinned frogs. It head-butts toxins 25 times as powerful as typical pit viper venom, a phenomenon luckily not discovered by handling.

Accidents are how most venomous animals first come to scientific notice, Brodie says. Early in his career, he discovered details of fire salamander venom by tickling a new specimen with a piece of grass. He was showing students how toxins ooze from its skin and “it sprayed me right in the eye,” he says. “I was immediately blinded.”

“I ran to the sink and ran water in my eye for about 20 minutes,” he says. “The toxin isn’t water soluble, so it didn’t help much. It was extraordinarily painful,” he notes in mild tones. Also, “the first time you observe something like that, you’re not sure it’s temporary blindness.” It was.

Venomous amphibians may be more common than people expect, Brodie says. Now that the researchers know about bone points for venom delivery, they want to investigate some salamanders with ribs that punch through the skin. And at least three more frogs grow suspicious spines around their heads. “It’s not Kermit anymore,” he says.

Editor’s Note: This story was updated on August 13, 2015, to clarify the habitat differences between the two venomous frogs.

Moving exhibit pays tribute to lost space shuttles’ crews

With the blessings of all 14 families of lost astronauts, a new memorial to the Challenger and Columbia space shuttle disasters opened in June at the Kennedy Space Center in Florida. The permanent exhibit includes the first pieces of shuttle wreckage ever on public display, but fittingly focuses more on the lives lost.

“Forever Remembered” is housed inside the space center’s new $100 million exhibit about the space shuttle Atlantis. Below the nose of the intact shuttle, visitors enter a hall lit by tributes to each astronaut from the lost missions, those from Challenger on the left and Columbia on the right. Each display includes glimpses of the astronaut’s life. Items include plans for remodeling the home of Challenger pilot Michael Smith and a recovered page in Hebrew from the Columbia flight journal of Ilan Ramon, a payload specialist and the first Israeli astronaut.
Past the hall, visitors enter a small gallery with a single piece of each shuttle: a body panel from Challenger (shown at left) and cockpit window frames from Columbia
. There are no extended written descriptions or flashy videos. In short, it’s a place for pondering rather than learning. As a ninth-grader in school 50 miles away when Challenger exploded in 1986 and as an adult who waited for a telltale sonic boom that never came when Columbia was lost during re-entry in 2003, I found the effect powerful.
The exhibit’s exit hallway reveals the tragedies from multiple perspectives on video displays. One video details the massive efforts to recover the wreckage and remains from the disasters, from the ocean for Challenger and from land for Columbia. Others focus on the emotional tolls and the critical shuttle launches that followed each completed investigation.

Michael Curie, Kennedy Space Center’s news chief, says family members have been both supportive and grateful for the exhibit. “They feel that it humanizes their family members in a way that never has been done before,” he says. Indeed, “Forever Remembered” is an effective reminder of the very real risks each astronaut willingly and bravely faced.

Boa suffocation is merely myth

Boa constrictors don’t so much suffocate prey as break their hearts. It turns out that the snakes kill like demon blood pressure cuffs, squeezing down circulation to its final stop. The notion that constrictors slay by preventing breathing turns out to be wrong.

The snakes don’t need limbs, or even venom, to bring down an animal of their own size. “Imagine you’re killing and swallowing a 150-pound animal in one meal — with no hands or legs!” animal ecologist Scott Boback tells his students at Dickinson College in Carlisle, Pa., to convey what extraordinary hunters snakes are. Speed matters with prey flailing claws, hooves or other weaponry the snake lacks. Embracing prey into heart failure is faster than suffocating it and appeared in different forms multiple times in snake history.
Ambushing birds, monkeys and a wide range of other animals from Mexico south to Argentina, the iconic Boa constrictor attacks in much the same way each time. The snake cinches a loop or two around the upper body of prey, pressing against its victim hard enough to starve organs of oxygenated blood.

“It’s not some unbelievable amount of pressure,” says Boback, whose arms get snaked now and then. “It stings a little — you can kind of feel the blood stop,” he says.
Within six seconds of looping around an anesthetized lab rat, a boa constrictor squeezes enough to halve blood pressure in a rear-leg artery. Blood that should surge through the artery lies dammed behind snake coils in the rat’s upper body. And back pressure keeps the rat heart from pumping out new blood. Circulation falters and fails. Boas release their grip after about six minutes on average, Boback and his colleagues report in the July 15 Journal of Experimental Biology.

Then the boa swallows the catch whole. A rat about a quarter of the snake’s weight disappears down the gullet in a couple of minutes. Moveable bones in the head help the snake make the gulp, as does a dimple of stretchy cartilage that lets the chin open wide. But what people most often tell Boback — that snake jaws must separate at the back — is just another serpentine myth.

Here’s why icicles made from pure water don’t form ripples

Icicles made from pure water give scientists brain freeze.

In nature, most icicles are made from water with a hint of salt. But lab-made icicles free from salt disobey a prominent theory of how icicles form, and it wasn’t clear why. Now, a study is helping to melt away the confusion.

Natural icicles tend to look like skinny cones with rippled surfaces — the result of a thin film of water that coats the ice, researchers think (SN: 11/24/13). As icicles grow, the film freezes. Any preexisting small bumps in the icicle get magnified into large ripples because the water layer is thinner above the bumps and can freeze more readily. But this theory fails to explain the salt-free variety, which have more irregular shapes reminiscent of drippy candles, says physicist Menno Demmenie of the University of Amsterdam.
So Demmenie and colleagues grew icicles in the lab, adding a blue dye that was visible only when the water was liquid. Salted icicles not only had ripples, but they also were covered in a thin, blue film. Icicles made from pure water had no such film. Only small droplets of blue appeared on those icicles, the team reports in the February Physical Review Applied.

In icicles with salt, the temperature at which the water on the surface freezes is lowered, allowing a liquid layer to coat the entire icicle. Without the salt, icicles must build up drop by drop.

Why male giraffes drink potential mates’ pee

A female giraffe has a great Valentine’s Day gift for potential mates: urine.

Distinctive anatomy helps male giraffes get a taste for whether a female is ready to mate, animal behaviorists Lynette and Benjamin Hart report January 19 in Animals. A pheromone-detecting organ in giraffes has a stronger connection to the mouth than the nose, the researchers found. That’s why males scope out which females to mate with by sticking their tongues in a urine stream.
Animals such as male gazelles will lick fresh urine on the ground to track if females are ready to mate. But giraffes’ long necks and heavy heads make bending over to investigate urine on the ground an unstable and vulnerable position, says Lynette Hart, of the University of California, Davis.

The researchers observed giraffes (Giraffa giraffa angolensis) in Etosha National Park in Namibia in 1994, 2002 and 2004. Bull giraffes nudged or kicked the female to ask her to pee. If she was a willing participant, she urinated for a few seconds, while the male took a sip. Then the male curled his lip and inhaled with his mouth, a behavior called a flehmen response, to pull the female’s scent into two openings on the roof of the mouth. From the mouth, the scent travels to the vomeronasal organ, or VNO, which detects pheromones.

The Harts say they never saw a giraffe investigate urine on the ground.

Unlike many other mammals, giraffes have a stronger oral connection — via a duct — to the VNO, than a nasal one, examinations of preserved giraffe specimens showed. One possible explanation for the difference could be that a VNO-nose link helps animals that breed at specific times of the year detect seasonal plants, says Benjamin Hart, a veterinarian also at the University of California, Davis. But giraffes can mate any time of year, so the nasal connection may not matter as much.

The James Webb telescope spotted the earliest known ‘quenched’ galaxy

The James Webb Space Telescope has spotted the earliest known galaxy to abruptly stop forming stars.

The galaxy, called GS-9209, quenched its star formation more than 12.5 billion years ago, researchers report January 26 at That’s only a little more than a billion years after the Big Bang. Its existence reveals new details about how galaxies live and die across cosmic time.

“It’s a remarkable discovery,” says astronomer Mauro Giavalisco of the University of Massachusetts Amherst, who was not involved in the new study. “We really want to know when the conditions are ripe to make quenching a widespread phenomenon in the universe.” This study shows that at least some galaxies quenched when the universe was young.
GS-9209 was first noticed in the early 2000s. In the last few years, observations with ground-based telescopes identified it as a possible quenched galaxy, based on the wavelengths of light it emits. But Earth’s atmosphere absorbs the infrared wavelengths that could confirm the galaxy’s distance and that its star-forming days were behind it, so it was impossible to know for sure.

So astrophysicist Adam Carnall and colleagues turned to the James Webb Space Telescope, or JWST. The observatory is very sensitive to infrared light, and it’s above the blockade of Earth’s atmosphere (SN: 1/24/22). “This is why JWST exists,” says Carnall, of the University of Edinburgh. JWST also has much greater sensitivity than earlier telescopes, letting it see fainter, more distant galaxies. While the largest telescopes on the ground could maybe see GS-9209 in detail after a month of observing, “JWST can pick this stuff up in a few hours.”

Using JWST observations, Carnall and colleagues found that GS-9209 formed most of its stars during a 200-million-year period, starting about 600 million years after the Big Bang. In that cosmically brief moment, it built about 40 billion solar masses’ worth of stars, about the same as the Milky Way has.

That quick construction suggests that GS-9209 formed from a massive cloud of gas and dust collapsing and igniting stars all at once, Carnall says. “It’s pretty clear that the vast majority of the stars that are currently there formed in this big burst.”

Astronomers used to think this mode of galaxy formation, called monolithic collapse, was the way that most galaxies formed. But the idea has fallen out of favor, replaced by the notion that large galaxies form from the slow merging of many smaller ones (SN: 5/17/21).

“Now it looks like, at least for this object, monolithic collapse is what happened,” Carnall says. “This is probably the clearest proof yet that that kind of galaxy evolution happens.”
As to what caused the galaxy’s star-forming frenzy to suddenly stop, the culprit appears to be an actively feeding black hole. The JWST observations detected extra emission of infrared light associated with a rapidly swirling mass of energized hydrogen, which is a sign of an accreting black hole. The black hole appears to be up to a billion times the mass of the sun.

To reach that mass in less than a billion years after the birth of the universe, the black hole must have been feeding even faster earlier on in its life, Carnall says (SN: 3/16/18). As it gorged, it would have collected a glowing disk of white-hot gas and dust around it.

“If you have all that radiation spewing out of the black hole, any gas that’s nearby is going to be heated up to an incredible extent, which stops it from falling into stars,” Carnall says.

More observations with future telescopes, like the planned Extremely Large Telescope in Chile, could help figure out more details about how the galaxy was snuffed out.

These chemists cracked the code to long-lasting Roman concrete

MIT chemist Admir Masic really hoped his experiment wouldn’t explode.

Masic and his colleagues were trying to re-create an ancient Roman technique for making concrete, a mix of cement, gravel, sand and water. The researchers suspected that the key was a process called “hot mixing,” in which dry granules of calcium oxide, also called quicklime, are mixed with volcanic ash to make the cement. Then water is added.

Hot mixing, they thought, would ultimately produce a cement that wasn’t completely smooth and mixed, but instead contained small calcium-rich rocks. Those little rocks, ubiquitous in the walls of the Romans’ concrete buildings, might be the key to why those structures have withstood the ravages of time.
That’s not how modern cement is made. The reaction of quicklime with water is highly exothermic, meaning that it can produce a lot of heat — and possibly an explosion.

“Everyone would say, ‘You are crazy,’” Masic says.

But no big bang happened. Instead, the reaction produced only heat, a damp sigh of water vapor — and a Romans-like cement mixture bearing small white calcium-rich rocks.

Researchers have been trying for decades to re-create the Roman recipe for concrete longevity — but with little success. The idea that hot mixing was the key was an educated guess.

Masic and colleagues had pored over texts by Roman architect Vitruvius and historian Pliny, which offered some clues as to how to proceed. These texts cited, for example, strict specifications for the raw materials, such as that the limestone that is the source of the quicklime must be very pure, and that mixing quicklime with hot ash and then adding water could produce a lot of heat.

The rocks were not mentioned, but the team had a feeling they were important.
“In every sample we have seen of ancient Roman concrete, you can find these white inclusions,” bits of rock embedded in the walls. For many years, Masic says, the origin of those inclusions was unclear — researchers suspected incomplete mixing of the cement, perhaps. But these are the highly organized Romans we’re talking about. How likely is it that “every operator [was] not mixing properly and every single [building] has a flaw?”

What if, the team suggested, these inclusions in the cement were actually a feature, not a bug? The researchers’ chemical analyses of such rocks embedded in the walls at the archaeological site of Privernum in Italy indicated that the inclusions were very calcium-rich.

That suggested the tantalizing possibility that these rocks might be helping the buildings heal themselves from cracks due to weathering or even an earthquake. A ready supply of calcium was already on hand: It would dissolve, seep into the cracks and re-crystallize. Voila! Scar healed.

But could the team observe this in action? Step one was to re-create the rocks via hot mixing and hope nothing exploded. Step two: Test the Roman-inspired cement. The team created concrete with and without the hot mixing process and tested them side by side. Each block of concrete was broken in half, the pieces placed a small distance apart. Then water was trickled through the crack to see how long it took before the seepage stopped.

“The results were stunning,” Masic says. The blocks incorporating hot mixed cement healed within two to three weeks. The concrete produced without hot mixed cement never healed at all, the team reports January 6 in Science Advances.

Cracking the recipe could be a boon to the planet. The Pantheon and its soaring, detailed concrete dome have stood nearly 2,000 years, for instance, while modern concrete structures have a lifespan of perhaps 150 years, and that’s a best case scenario (SN: 2/10/12). And the Romans didn’t have steel reinforcement bars shoring up their structures.

More frequent replacements of concrete structures means more greenhouse gas emissions. Concrete manufacturing is a huge source of carbon dioxide to the atmosphere, so longer-lasting versions could reduce that carbon footprint. “We make 4 gigatons per year of this material,” Masic says. That manufacture produces as much as 1 metric ton of CO2 per metric ton of produced concrete, currently amounting to about 8 percent of annual global CO2 emissions.

Still, Masic says, the concrete industry is resistant to change. For one thing, there are concerns about introducing new chemistry into a tried-and-true mixture with well-known mechanical properties. But “the key bottleneck in the industry is the cost,” he says. Concrete is cheap, and companies don’t want to price themselves out of competition.

The researchers hope that reintroducing this technique that has stood the test of time, and that could involve little added cost to manufacture, could answer both these concerns. In fact, they’re banking on it: Masic and several of his colleagues have created a startup they call DMAT that is currently seeking seed money to begin to commercially produce the Roman-inspired hot-mixed concrete. “It’s very appealing simply because it’s a thousands-of-years-old material.”

These adorable Australian spike-balls beat the heat with snot bubbles

Animals cover themselves in all kinds of unsavory fluids to keep cool. Humans sweat, kangaroos spit and some birds will urinate on themselves to survive hot days. It turns out that echidnas do something much cuter — though perhaps just as sticky (and slightly icky) — to beat the heat.

The spiny insectivores stay cool by blowing snot bubbles, researchers report January 18 in Biology Letters. The bubbles pop, keeping the critters’ noses moist. As it evaporates, this moisture draws heat away from a blood-filled sinus in the echidna’s beak, helping to cool the animal’s blood.
Short-beaked echidnas (Tachyglossus aculeatus) look a bit like hedgehogs but are really monotremes — egg-laying mammals unique to Australia and New Guinea (SN: 11/18/16). Previous lab studies showed that temperatures above 35° Celsius (95° Fahrenheit) should kill echidnas. But echidnas don’t seem to have gotten the memo. They live everywhere from tropical rainforests to deserts to snow-capped peaks, leaving scientists with a physiological puzzle.

Mammals evaporate water to keep cool when temperatures climb above their body temperatures, says environmental physiologist Christine Cooper of Curtin University in Perth, Australia. “Lots of mammals do that by either licking, sweating or panting,” she says. “Echidnas weren’t believed to be able to do that.” But it’s known that the critters blow snot bubbles when it gets hot.

So, armed with a heat-vision camera and a telephoto lens, Cooper and environmental physiologist Philip Withers of the University of Western Australia in Perth drove through nature reserves in Western Australia once a month for a year to film echidnas.

In infrared, the warmest parts of the echidnas’ spiny bodies glowed in oranges, yellows and whites. But the video revealed that the tips of their noses were dark purple blobs, kept cool as moisture from their snot bubbles evaporated. Echidnas might also lose heat through their bellies and legs, the researchers report, while their spikes could act as an insulator.
“Finding a way of doing this work in the field is pretty exciting,” says physiological ecologist Stewart Nicol of the University of Tasmania in Hobart, Australia, who was not involved in the study. “You can understand animals and see how they’re responding to their normal environment.” The next step, he says, is to quantify how much heat echidnas really lose through their noses and other body parts.

Monotremes parted evolutionary ways with other mammals between 250 million and 160 million years ago as the supercontinent Pangaea broke apart (SN: 3/8/15). So “they have a whole lot of traits that are considered to be primitive,” Cooper says. “Understanding how they might thermoregulate can give us some ideas about how thermal regulation … might have evolved in mammals.”

Scientists have found the first known microbes that can eat only viruses

Tiny, pond-dwelling Halteria ciliates are virovores, able to survive on a virus-only diet, researchers report December 27 in Proceedings of the National Academy of Sciences. The single-celled creatures are the first known to thrive when viruses alone are on the menu.

Scientists already knew that some microscopic organisms snack on aquatic viruses such as chloroviruses, which infect and kill algae. But it was unclear whether viruses alone could provide enough nutrients for an organism to grow and reproduce, says ecologist John DeLong of the University of Nebraska–Lincoln.
In laboratory experiments, Halteria that were living in water droplets and given only chloroviruses for sustenance reproduced, DeLong and colleagues found. As the number of viruses in the water dwindled, Halteria numbers went up. Ciliates without access to viral morsels, or any other food, didn’t multiply. But Paramecium, a larger microbe, didn’t thrive on a virus-only diet, hinting that viruses can’t satisfy the nutritional requirements for all ciliates to grow.

Viruses could be a good source of phosphorus, which is essential for making copies of genetic material, DeLong says. But it probably takes a lot of viruses to account for a full meal.

In the lab, each Halteria microbe ate about 10,000 to 1 million viruses daily, the team estimates. Halteria in small ponds with abundant viral snacks might chow down on about a quadrillion viruses per day.

These feasts could shunt previously unrecognized energy into the food web, and add a new layer to the way viruses move carbon through an ecosystem — if it happens in the wild, DeLong says (SN: 6/9/16). His team plans to start finding out once ponds in Nebraska thaw.