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Why We Can’t Stop Seeing Zigzags in This Freaky Optical Illusion

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Why We Can't Stop Seeing Zigzags in This Freaky Optical Illusion

An example of the curvature blindness illusion. What do you see in the middle: wavy lines, angular lines, or both?

Credit: Kohske Takahashi

Who would win in a fight: the part of the brain that likes to see curves or the part that prefers corners?

This conflict underlies a new kind of optical illusion, dubbed the “curvature blindness illusion” in a new paper published in the November-December issue of the journal i-Perception.

Kohske Takahashi, an associate professor of experimental psychology at Japan’s Chukyo University, showed a small sample of students the image below and asked them a simple question: What do you see in the gray, middle section of this picture — curved lines, angled lines or both? [The Most Amazing Optical Illusions (And How They Work)]

If you see alternating rows of wavy and zigzagging lines (like all study participants did), you’re both right and wrong. The truth is, every line in this image is an identical, wavy shape. And yet, our brains reliably see sharp-cornered zigzags stitched across the middle section of the image. The reason this illusion works so well is unclear, but Takahashi offers a few hypotheses in his paper.

For one, Takahashi writes in the paper, it seems likely from this curvature blindness illusion (as well as from previous illusion research) that the human brain has separate mechanisms for identifying curved shapes and angular shapes, and that these mechanisms tend to interfere or compete with each other.

Takahashi reached this conclusion after trying to deconstruct the illusion across three experiments. He showed participants several variations on the illusion, changing details like the height of the curves, the color of the background (black, white or gray), and whether the lines changed color at the peak of the curve or on either side of it. He found that the only conditions that made the curved lines reliably appear zigzagged were: when the lines had a gentle curve, when the lines changed color directly before and after the peaks or valleys of each curve, and when the lines appeared over a gray background that contrasted the light and dark tones of each line.

An example of the curvature blindness illusion. What do you see in the middle: wavy lines, angular lines, or both?

An example of the curvature blindness illusion. What do you see in the middle: wavy lines, angular lines, or both?

Credit: Kohske Takahashi

The final image of the illusion reflects these findings: Every line appears curved when seen over the white and black backgrounds, while in the gray, middle section, only lines that change color right before and after the peaks of the curves seem to be zigzagged. When the two colors meet at the curve’s peak, they create a subtle vertical line that exaggerates the peak’s sharpness.

Takahashi hypothesized that when the curve- and angle-perception mechanisms of the brain work side by side with similar inputs like these, angles take priority.

“We propose that the underlying mechanisms for the gentle-curve perception and those of obtuse-corner perception are competing with each other in an imbalanced way and the [perceptions of corners] might be dominant in the visual system,” Takahashi wrote.

So, whoever had money on corners in the curves vs. corners matchup wins.

Originally published on Live Science.

Giant Penguin: This Ancient Bird Was As Tall As a Refrigerator


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Giant Penguin: This Ancient Bird Was As Tall As a Refrigerator

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Giant Penguin: This Ancient Bird Was As Tall As a Refrigerator

The giant penguin Kumimanu biceae was likely as tall as a human.

Credit: G. Mayr/Senckenberg Research Institute

The fossils of a refrigerator-size penguin were so gargantuan that the scientists who discovered them initially thought they belonged to a giant turtle. The ancient behemoth is now considered the second-largest penguin on record.

The newfound penguin species would have stood nearly 6 feet tall (1.8 meters) and weighed about 220 lbs. (100 kilograms) during its heyday tens of millions of years ago.

The bird’s gigantism indicates that “a very large size seems to have developed early on in penguin evolution, soon after these birds lost their flight capabilities,” said study co-lead researcher Gerald Mayr, a curator of ornithology at the Senckenberg Research Institute, in Germany. [In Photos: The Amazing Penguins of Antarctica]

At first, the researchers thought the penguin fossils belonged to a turtle, said study co-lead researcher Alan Tennyson, a vertebrate curator at the Museum of New Zealand (Te Papa Tongarewa), who discovered the fossil with paleontologist Paul Scofield on a beach in New Zealand’s Otago province in 2004.

But shortly after a fossil technician began preparing the specimen in 2015, he found a part of the shoulder blade, known as the coracoid, which revealed that the fossils came from a penguin, Tennyson told Live Science.

The rectangles over this <i>Kumimanu biceae</i> fossil emphasize the humerus and a bone from the shoulder girdle (coracoid), which are shown separated from the original bone cluster.

The rectangles over this Kumimanu biceae fossil emphasize the humerus and a bone from the shoulder girdle (coracoid), which are shown separated from the original bone cluster.

Credit: G. Mayr/Senckenberg Research Institute

Further analysis dated the penguin to between 55 million and 59 million years ago, meaning that it lived a mere 7 million to 11 million years after an asteroid slammed into Earth and killed the nonavian dinosaurs, Mayr said.

The researchers named the late-Paleocene penguin Kumimanu biceae. Its genus name, Kumimanu, was inspired by the Maori indigenous culture of New Zealand. In the Maori culture, “kumi” is a mythological monster, and “manu” is the Maori word for “bird.” The species name, biceae, honors Tennyson’s mother, Beatrice “Bice” A. Tennyson, who encouraged him to pursue his interest in natural history.

K. biceae didn’t look much like modern penguins. Although researchers could not find its skull, they “know from similarly aged fossils that the earliest penguins had much longer beaks, which they probably used to spear fishes, than their modern relatives [do],” Mayr told Live Science. Like its modern cousins, however, K. biceae would have already developed typical penguin feathers, waddled with an upright stance and sported flipper-like wings that helped it swim, he added.

Researchers have discovered other ancient penguin fossils in New Zealand, including those of Waimanu manneringi, which lived about 61 million years ago. However, the largest penguin on record isPalaeeudyptes klekowskii, which lived about 37 million years ago in Antarctica. P. klekowskii stood about 6.5 feet (2 m) tall and weighed a whopping 250 lbs. (115 kg), according to a 2014 study in the journal Comptes Rendus Palevol (Palevol Reports).

The upper arm bone, known as the humerus (top) and a bone from the shoulder girdle (coracoid, bottom) of the Paleocene giant penguin <i>Kumimanu biceae</i>, compared with the corresponding bones of one of the largest fossil penguins known to date, <i>Pachydyptes ponderosus</i> (from the Eocene epoch in New Zealand), and those of a modern emperor penguin (<i>Aptenodytes forsteri</i>).

The upper arm bone, known as the humerus (top) and a bone from the shoulder girdle (coracoid, bottom) of the Paleocene giant penguin Kumimanu biceae, compared with the corresponding bones of one of the largest fossil penguins known to date, Pachydyptes ponderosus (from the Eocene epoch in New Zealand), and those of a modern emperor penguin (Aptenodytes forsteri).

Credit: G. Mayr/Senckenberg Research Institute

Given that the Antarctic penguin was larger than K. biceae, it’s likely that “giant size evolved more than once in penguin evolution,” Mayr said.

K. biceae is a “cool fossil,” said Daniel Ksepka, a curator at the Bruce Museum in Greenwich, Connecticut, who was not involved in the research. “It’s very old; it’s almost as old as the oldest known penguins anywhere,” Ksepka told Live Science. “That shows that [penguins] got big really quickly. And it all seems to have happened in New Zealand.” [Photos of Flightless Birds: All 18 Penguin Species]

But why was New Zealand a penguin paradise? The archipelago was surrounded by fish for penguins to eat, and it originally had no native mammals (although today it’s home to many sheep, weasels and domestic pets), meaning that there were no predators to bother the penguins when they came ashore to molt their feathers and lay eggs, Ksepka said.

The study was published online today (Dec. 12) in the journal Nature Communications.

An artist's interpretation of <i>Kumimanu biceae</i>, the second-largest penguin on record.

An artist’s interpretation of Kumimanu biceae, the second-largest penguin on record.

Credit: G. Mayr/Senckenberg Research Institute

Original article on Live Science.

This 5,000-Pound Behemoth Is the World’s Heaviest Bony Fish


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This 5,000-Pound Behemoth Is the World’s Heaviest Bony Fish

 This 5,000-Pound Behemoth Is the World's Heaviest Bony Fish
The new “largest bony fish” (Mola alexandrine) was originally misidentified as a Mola mola sunfish, which is shown in this image with diver Daniel Botelho in San Diego, California.

Credit: Daniel Botelho/Barcroft Media via Getty Images

The heaviest bony fish ever caught weighs in at a staggering 5,070 lbs. (2,300 kilograms). Now, scientists know its name.

The fish is a Mola alexandrini ocean sunfish, researchers reported Dec. 5 in the journal Ichthyological Research. Originally, the fish, which was caught in 1996, was misidentified as a Mola mola, a better-known species of sunfish. But recent research has upended the whole Mola genus and led to the reidentification of some species. M. alexandrini is recognizable by its prominent head shape, lending it the common name the “bump-headed sunfish.”

“For the same reason, we adopt the already proposed Japanese common name Ushi-manbo,” said study leader Etsuro Sawai, a sunfish expert at Hiroshima University. “‘Ushi’ means ‘cow,’ and refers to the head profile of the fish.” [In Photos: The World’s Largest Bony Fish]

Sunfish are the largest bony fish in the sea. Unlike sharks and rays, they have skeletons made of bone rather than cartilage. They’re also very strange-looking. Their bodies are huge and round, shaped like wagon wheels or pancakes. They can grow up to about 10 feet (3 meters) long.

The Mola genus wasn’t well understood until in recent years, because studying such enormous specimens isn’t easy. They’re difficult to collect and even harder to transport for thorough anatomical examinations. Genetic studies cracked open the case, revealing that fish once classified as Mola mola were in fact very different from one another, and that some gene sequences didn’t fit nicely into pre-existing species categories. In July 2017, researchers named a new species of sunfish with those sequences,Mola tecta, after finding a handful of specimens washed ashore on a New Zealand beach.

M. tecta has a round snout and a distinctive stripe that divides its body from the rudder-type fin on the fish, which is known as the clavus.

In the new study, researchers studied 30 specimens of Mola that did not belong to the M. tecta species. They also hunted through historical photographs, looking for anatomical features that would help to distinguish existing species from one another. Ultimately, they used this information to redescribe M. alexandrini and to differentiate it from M. tecta and M. mola.

The realization that M. alexandrini wins the heavyweight prize for bony fish grew out of this newly clarified classification. Guinness World Records listsM. mola as the world’s heaviest bony fish, but Sawai and his team found that the largest catch on record was actually a M. alexandrini caught in 1996 off Kamogawa, Japan. That fish was 8.9 feet (2.72 m) long, raising the question of whether some individuals of this species are even heavier. In 2004, fishers recorded the catch of a 10.9-foot-long (3.32 m) M. alexandrininear Aji Island, Japan, but they didn’t weigh that behemoth.

Original article on Live Science.

The Life of a Baby Tardigrade


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The Life of a Baby Tardigrade

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The Life of a Baby Tardigrade

Vladimir Gross used a scanning electron microscope to capture this image of a tiny, 50-hour-old tardigrade embryo.

Credit: Vladimir Gross

It started as a speck of a speck, a bundle of nerves and immature tissues curled up inside an egg, bunched up against its siblings. The small clutch of embryonic water bears was immobile, silent, unseeing and possibly unfeeling. Locked away inside their mother’s ovaries, they waited to be born.

One of nearly 1,000 species of hardy tardigrades, the Hypsibius dijardiniembryo pictured above may have been the product of a sexless act of reproduction, its mother squirting her genetic material directly into eggs without bothering with any of the handful of males of her species for fertilization, according to the Encyclopedia of Life. That reproductive ability (called parthenogenesis), a genetic heritage largely unchanged through the generations, was her birthright and one she would likely have passed down to her children.

Tardigrades are among the hardiest animals on planet Earth, resistant to heat and cold, radiation and extreme dehydration. This H. dijardini embryo would have eventually emerged from its egg fully formed, and as ready to take on those horrors as her mother had been. Tardigrades, as researchers studying them way back in 1938 for a paper in American Midland Naturalist discovered, have no childhood. They pierce through their eggs small, but fully formed.

The embryo captured by photographer Vladimir Gross is 50 hours old, nearing readiness to emerge. All of her limbs, mouth parts and most of her organs developed over the course of those hours, before and after her mother squeezed her out into the world. (Gross snagged runner-up in the Royal Society Publishing Photography Competition’s Microimaging category.)

https://player.vimeo.com/video/70687289?title=0&byline=0&portrait=0

When the egg-enclosed baby was ready, the 1938 researchers discovered, she would have driven her mouthparts into the wall of her egg, carved a small hole, and wriggled through it into her new life. Her organs, streamlined for digestion and reproduction, would already be churning. She wouldn’t swim through her wet world, but would instead get around on her eight stubby, clawed legs.

If she were in the wild, she would have gotten to work munching on the wet mosses and small plants where she would have made her home. And with all the food she would take in, she would grow. Over the course of her lifetime, she could expect to cast off her outer skin several times to make room for her growing body, according to a study published in 2015 in the journal Polar Biology.

According to The Encyclopedia of Life, she would have been ready to give birth to her first batch of eggs within two weeks of her own birth — between one and 30 tardigrade embryos, depending on how much food she’d had available. Some species of tardigrade lay eggs inside their cast-off skins. Some wait for males to fertilize them, but not H. dijardini. Except in unusual circumstances, which scientists still do not fully understand, she would create eggs with near-exact copies of her genetic code, just like her mother had with her.

She could expect to birth several more clutches of eggs in her life, which would last another 70 or so days — unless, of course, she were frozen or dehydrated, in which case she might live on in a dormant state for months, years, decades or longer, until the world was ready for her again. Then she would wake up, and get right back to the business of being a water bear.

Originally published on Live Science.