Tag: Biology

Zoologists Explained Why The Ostrich Is The Only Living Animal With Four Kneecaps

According to experts, the unusual structure of the legs allows the bird to accelerate quickly.

Ostrich is one of the most interesting and unusual birds in the modern world. He can’t fly but runs very fast and has the largest size among the brethren.

In addition, the ostrich is the only living creature on Earth with four knees.




After a series of studies, scientists have created a computer model of the leg of the ostrich. This allowed them to understand why the “extra” body parts of this bird has not disappeared with evolution.

As it turned out, four knee ostriches need for rapid response to possible danger. When a member of the species feels the approach of the enemy, he may suddenly break away from their homes, developing a decent speed.

In this case the leg bone of an ostrich face enormous pressure, while a special mechanism reduces the load. That is part of it and are knees.

Zoologists said that while not believe in his theory 100%. Researchers simply have nothing to compare the results of their work, since 1884, on the Ground there are no other organisms with four knees, in addition to ostriches.

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The Prehistoric Puzzle Of How Plesiosaurs Swam Through The Oceans

Among the stranger creatures to roam the earth during the time of the dinosaurs was not a dinosaur at all, but a marine reptile — the plesiosaur.

This odd predator navigated Mesozoic Era waters with four flippers — two in the front and two in the back — a design unlike anything seen in modern-day swimmers.

How the plesiosaur actually used its limbs to swim has remained something of a mystery.

But in a study in the journal PLOS Computational Biology, a group of scientists has used computer modeling to pin down what those strokes might have looked like — and it turns out that they probably looked a lot like a penguin’s.




Plesiosaurs were a diverse group of swimming reptiles that thrived for 135 million years, from the Early Jurassic to the Late Cretaceous period (when they were wiped out by the same asteroid that took out the dinosaurs).

Some had long necks, others had short stubby ones, but all of them had this four-flippered body plan, where the animals’ legs had evolved into two pairs of wing-like appendages — “a unique adaptation in the animal Kingdom,” the study authors wrote.

Although plesiosaurs were a key component of Mesozoic marine ecosystems, there are no extant ‘four-winged’ analogues to provide insights into their behavior or ecology, and their locomotion has remained a topic of debate since the first complete plesiosaur skeleton was described in 1824,” the authors wrote.

Without any clear modern comparisons, how theirs flippers worked together has stumped scientists.

Some have argued that the plesiosaur had a rowing stroke, using its fins like boat oars; others argued for a “flight stroke,” rather like those of penguins and turtles, or a modified flight stroke like the ones sea lions use.

The extinct animals’ swimming motion has been equally up for grabs: Some have posited synchronous motion, with all four flippers moving in the same direction at the same time.

Others have favored semi-synchronous or asynchronous motion, where the forelimbs and hindlimbs move out-of-phase relative to each other.

Researchers haven’t even been able to agree on whether it was the forelimbs or the hindlimbs producing most of the animal’s thrust.

Scientists have tried all kinds of ways to model the animals’ swimming behavior, from using experimental robots to testing out human swimmers using paddles.

These studies, although informative, are limited because they do not deal with accurate representations of the plesiosaur form,” the study authors wrote.

There is therefore still no consensus on how plesiosaurs swam, especially how they moved all four limbs relative to each other.”

To get a better handle on plesiosaur physiology, researchers from Georgia Tech decided to build a computer model — far more accurate than, say, a human with some paddles.

They based theirs on Meyerasaurus victor, a Lower Jurassic plesiosaur from what is now Germany that would have stretched about 11 feet (relatively small by plesiosaur standards).

This model also allowed researchers to test thousands of simulations to try to determine which combinations of movement allowed the animal to move most effectively through the water.

In the end, the scientists found that the plesiosaur was swimming mostly with its forelimbs; surprisingly, the hindlimbs didn’t generate much thrust and likely were used for balance and steering.

Within the biologically possible range of limb motion, the simulated plesiosaur swims primarily with its forelimbs using an unmodified underwater flight stroke, essentially the same as turtles and penguins,” the study authors wrote.

Now that the scientists have developed a working model of this plesiosaur, they can use it to further probe exactly how the hindlimbs were used — and to explore the motion of other extinct swimming animals.

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These Gourmet Snakes Prefer To Eat Snails

Showin’ off those baby blues.

There’s something strange about the five newly discovered snakes in Ecuador: Unlike most snakes that dine on rats, lizards and other small animals, these slithery reptiles eat snails.

And that’s pretty much all these snakes can eat. There are now 75 known species of snail-eaters, according to a new study on the reptiles.

The jaws of these snakes are modified so much that they cannot eat anything that isn’t a snail or a slug,” said lead study author Alejandro Arteaga, a doctoral student with the American Museum of National History in New York.

Sometimes, you can see [one] hanging from vegetation with a snail in its mouth,” he said.

Indeed, snail-eating snakes have a jawline that has evolved to slurp the snail right out of its shell — but the snakes do this without suction (in other words, it’s not the way we slurp oysters from a shell).

To extract their escargot, the snakes push their lower jaws into the shell and grasp the flesh of the slimy critter with their curved teeth.




Once the snakes have a firm grasp, they pull the prey out without crushing the shell — a process that usually takes a few minutes.

This snail-slurping “is an interesting adaptation,” Arteaga told Live Science. Because not many snakes feed on these snails, the predators don’t have much competition for food, he added.

But the snakes have other things to worry about.

Arteaga and his team are proposing that three of the five species should be listed as “vulnerable” under the International Union for Conservation of Nature’s Red List of Threatened Species and that one should be listed as endangered.

Four of them are facing the possibility of extinction. Only one is safe,” Arteaga said.

The reason? A lack of cover for the snakes to hide in.

In western Ecuador, “only 2 percent of the original vegetation cover remains,” Arteaga said. The rest of the forest cover and vegetation was destroyed by activities like logging and clearing land for cattle farming and human settlement.

Ultimately, there’s “not really much forest left,” Arteaga said, and that’s not good for the snakes, who need forest cover, vegetation, moisture and nearby streams to survive. “They cannot survive in open cattle ranch [or] grassland.”

Arteaga and his team recently held an auction for the “naming rights” to the snakes.

With the money from that auction, the researchers will purchase a 178-acre (72 hectares) plot of currently unprotected land where some of these snakes live and thereby expand the Buenaventura Reserve in Ecuador.

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The Space Station Is Becoming A Spy Satellite For Wildlife

In 1250, the prior of a Cistercian Abbey reputedly tied a note to a leg of a barn swallow, which read: “Oh swallow, where do you live in winter?” The next spring, he got a response: “In Asia, in the home of Petrus.

This perhaps apocryphal story marks one of the first known instances of someone tagging an animal to track its movements.

Thanks to many such endeavors, we now know that every year, barn swallows migrate between their breeding grounds in the northern hemisphere to wintering grounds throughout the tropics and the south.

In 1912, one intrepid individual that was ringed in England turned up 7,500 miles away in South Africa.

But swallows are the exception rather than the rule. The journeys of most migratory animals, especially smaller species, are a mystery.




Flocks, herds, and shoals are constantly crisscrossing the globe, but despite the intense surveillance of our planet, we often have no idea what paths they take.

They leave in one place and we don’t know what happens to them until they show up in another place,” says Meg Crofoot from the University of California, Davis.

This ignorance makes it hard to save threatened species: what works in one part of the world may be completely undone as animals travel to another. It also jeopardizes our own health.

Where are the birds that harbor avian flu? Where do the bats that carry Ebola go? What about the red-billed quelea, a small finch that flocks in millions and devours crops with locust-like voraciousness?

Since the 1960s, scientists have tried to answer questions like these by tagging animals with radio transmitters. At first, they followed the signals with clunky hand-held antennae.

Later, they loaded receivers onto satellites, allowing them to track animals over long distances and rough terrain.

But even after decades of innovation, satellite telemetry tags are still expensive, slow, and clunky. The smallest weighs around 10 grams and would overburden any animal lighter than 240 grams.

That rules out three quarters of birds and mammals. There are much lighter data-loggers around but they’re light because they don’t transmit any data—so you have to recapture whatever animal you’ve tagged to find out where it has been.

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5 Hard-Shelled Facts About Horseshoe Crabs

The plodding sea creatures have weird blood, weirder swimming habits, and a secret weapon that’s probably saved your life.

1. HORSESHOE CRABS ARE INCREDIBLY OLD.

Discovered in 2008, the 25 millimeter-wide Lunataspis aurora crawled over Manitoba 445 million years ago. This makes it the world’s oldest-known horseshoe crab.

Four species are with us today, all of which closely resemble their long-extinct ancestors.

Supposedly frozen in time, horseshoe crabs are often hailed as “living fossils” by the media.




Yet, appearances can be misleading. Evolution didn’t really leave these invertebrates behind. They’ve transformed quite a bit over the past half-billion years.

For instance, some prehistoric species had limbs that split out into two branches, but today’s specimens have only one.

2. THEY’RE NOT CRABS.

In fact, they aren’t even crustaceans. Unlike real crabs and their kin, horseshoe “crabs” lack antennae.

So, where do the strange ocean-dwellers belong on the arthropod family tree? Biologists classify them as chelicerates, a subphylum that also includes arachnids.

Members possess two main body segments and a pair of unique, pincer-like feeding appendages called chelicerae.

3. EACH ONE HAS A HUGE ARRAY OF SIGHT ORGANS.

Large compound eyes rest on the sides of their shells. Come mating season, these bean-shaped units help amorous crabs locate a partner. Behind each one, there’s a small, primitive photoreceptor called a lateral eye.

Towards the front of the shell are two tiny median eyes and a single endoparietal eye. On its underside, a horseshoe has two “ventral eyes,” which presumably help it navigate while swimming.

4. BABIES CAN SWIM UPSIDE DOWN.

Walking around on the ocean floor is generally how horseshoe crabs get from point A to point B.

Nevertheless, young ones will often flip over and start propelling themselves through the water, using their gills as extra paddles. With age, they do this less frequently.

5. THE SPIKED TAIL HAS SEVERAL USES.

Stinging isn’t one of them, despite what many falsely believe. Among its uses are assuming rudder duties and helping the arthropod right itself after getting stuck on its back.

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Meet The Russian Biologist Who Is Also A Pioneer Of Modern Genetics

Nikolai Konstantinovich Koltsov was a Russian biologist and a pioneer of modern genetics.

Koltsov graduated from Moscow University in 1894 and was a professor there (1895-1911).

He established and directed the Institute of Experimental Biology in the middle of 1917, just before the October revolution and was a member of the Agricultural Academy.

In 1920, Koltsov was arrested as a member of the non-existent “Anti-Soviet Tactical Center” invented by the VCheKa.

Prosecutor Nikolai Krylenko demanded the death sentence for Koltsov (67 of around 1000 arrested people were executed).

However, after a personal appeal to Vladimir Lenin by Maxim Gorky Koltsov was released and was restored to his position as the head of the Koltsov Institute of Experimental Biology.




Nikolai Koltsov worked on cytology and vertebrate anatomy. In 1903 Koltsov proposed that the shape of cells was determined by a network of tubules which he termed the cytoskeleton.

In 1927 Koltsov proposed that inherited traits would be inherited via a “giant hereditary molecule” which would be made up of “two mirror strands that would replicate in a semi-conservative fashion using each strand as a template“.

These ideas were confirmed to have been accurate in 1953 when James D. Watson and Francis Crick described the structure of DNA.

Watson and Crick had apparently not heard of Koltsov. US geneticist Richard Goldschmidt wrote about him: “There was the brilliant Nikolai Koltsov, probably the best Russian zoologist of the last generation, an enviable, unbelievably cultured, clear-thinking scholar, admired by everybody who knew him“.

In 1937 and 1939, the supporters of Trofim Lysenko published a series of propaganda articles against Nikolai Koltsov and Nikolai Vavilov.

They wrote: “The Institute of Genetics of the Academy of Sciences not only did not criticize Professor Koltsov’s fascistic nonsense, but even did not dissociate itself from his “theories” which support the racial theories of fascists“.

His death in 1940 was claimed to have been due to a stroke. However, the biochemist Ilya Zbarsky revealed that the unexpected death of Koltsov was a result of his poisoning by the NKVD, the secret police of the Soviet Union.

The same day his wife, the scientist Maria Sadovnikova Koltsova, committed suicide.

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Growing Human Brain Cells In The Lab

When researchers like Gan find potential new drugs, they must be tested on human cells to confirm they can benefit patients. Historically, these tests have been conducted in cancer cells, which often don’t match the biology of human brain cells.

The problem is that brain cells from actual people can’t survive in a dish, so we need to engineer human cells in the lab,” explained Gan, senior investigator at the Gladstone Institutes. “But, that’s not as simple as it may sound.”

Many scientists use induced pluripotent stem cells (iPSCs) to address this issue. IPSCs are made by reprogramming skin cells to become stem cells, which can then be transformed into any type of cell in the body.

Gan uses iPSCs to produce brain cells, such as neurons or glial cells, because they are relevant to neurodegenerative disease.




Human brain cells derived from iPSCs offer great potential for drug screening. Yet, the process for producing them can be complicated, expensive, and highly variable.

Many of the current methods produce cells that are heterogeneous, or different from one another, and this can lead to inconsistent results in drug screening.

In addition, producing a large number of cells is very costly, so it’s difficult to scale up for big experiments.

To overcome these constraints, Michael Ward, MD, PhD, had an idea.

A New Technique Is Born

I came across a new method to produce iPSCs that was developed at Stanford,” said Ward, a former postdoctoral scholar in Gan’s lab who is now an investigator at the National Institutes of Health.

I thought that if we could find a way to simplify and better control that approach, we might be able to improve the way we engineer human brain cells in the lab.”

Ward and his colleague Chao Wang, PhD, discovered a way to manipulate the genetic makeup of cells to produce thousands of neurons from a single iPSC. This meant that every engineered brain cell was now identical.

The team further improved the technique to create a simplified, two-step process. This allows scientists to precisely control how many brain cells they produce and makes it easier to replicate their results from one experiment to the next.

Their technique also greatly accelerates the process.

While it would normally take several months to produce brain cells, Gan and her team can now engineer large quantities of them within 1 or 2 weeks, and have functionally active neurons within 1 month.

The researchers realized this new approach had tremendous potential to screen drugs and to study disease mechanisms. To prove it, they tested it on their own research.

They applied their technique to produce human neurons by using iPSCs. Then, they developed a drug discovery platform and screened 1,280 compounds.

Their goal is to identify the compounds that could lower levels of the protein tau in the brain, which is considered one of the most promising approaches in Alzheimer’s research and could potentially lead to new drugs to treat the disease.

A Powerful Tool for the Entire Scientific Community

We have developed a cost-effective technology to produce large quantities of human brain cells in two simple steps,” summarized Gan.

By surmounting major challenges in human neuron-based drug discovery, we believe this technique will be adopted widely in both basic science and industry.

Word of this useful new technology has already spread, and people from different scientific sectors have come knocking on Gan’s door to learn about it.

Her team has shared the new method with scores of academic colleagues, some of whom had no experience with cell culture.

So far, they all successfully repeated the two-step process to produce their own cells and facilitate scientific discoveries.

Details of this new technique were also published on October 10, 2017, in the scientific journal Stem Cell Reports.

With some of the roadblocks out of the way, Gan hopes more discoveries will soon help the millions who suffer from Alzheimer’s disease.

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Fruit Bat’s Echolocation May Work Like Sophisticated Surveillance Sonar

The new open-access paper in PLoS Biology shows how the animals are able to navigate using a different system from other bats.

Before people thought that this bat was not really good at echolocation, and just made these simple clicks,” said lead author Wu-Jung Lee, a researcher at the UW’s Applied Physics Laboratory.

“But this bat species is actually very special — it may be using a similar technique that engineers have perfected for sensing remotely.”

While most other bats emit high-pitched squeals, the fruit bat simply clicks its tongue and produces signals that are more like dolphin clicks than other bats’ calls.

Fruit bats can also see quite well, and the animals switch and combine sensory modes between bright and dark environments.

An earlier study showed that Egyptian fruit bats send clicks in different directions without moving their head or mouth, and suggested that the animals can perform echolocation, the form of navigation that uses sound, better than previously suspected.




Lee and colleagues measured the animals in the “bat lab” at Johns Hopkins University by capturing high-speed video and ultrasonic audio of bats during flight to study the mechanism of their behavior and navigation.

In measuring echolocation signals from fruit bats with a three-dimensional array of microphones, Lee did not solve the mystery of the seemingly motionless tongue clicks, but she did notice something strange.

The beam of different frequencies of sound waves emitted by the bats do not align at the center and form a bullseye, as one would expect from a simple sound source, but instead the beam of sound is off-center at higher frequencies.

Lee recognized the pattern as a common one in radar and sonar surveillance systems.

Invented in the early 20th century and now used throughout civil and military applications, airplanes, ships and submarines emit pulses of radio waves in the air, or sound underwater, and then analyze the returning waves to detect objects or hazards.

While a simple single-frequency sonar has a tradeoff between the angular coverage and image sharpness, a “frequency-scanning sonar” solves this problem by pointing different frequencies of sound at slightly different angles to get fine-grained acoustic images over a large area.

Lee wondered if the fruit bats could be using the same technique when echolocating. She created a computer model of what might happen when the tongue click from the front of the mouth travels out and passes between the bat’s lips.

The elongated shape of the bat’s mouth creates varying distances between the sound source and the gaps between its teeth, and this creates positive or negative interference between sound waves of different frequencies.

The result, Lee’s model shows, is that different frequencies point in different directions — just as a frequency-scanning sonar would act.

For me, what’s exciting is the idea that you almost have a convergence between a system that was evolved, and the effects are very similar to what we have invented as humans,” Lee said.

“This is not the classic case where we learn from nature — we found out that the bat may be doing the same thing as a system we invented many years ago.”

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According To Scientists, Winged Archaeopteryx Dinosaur Flew In Short Bursts Like A Pheasant

Archaeopteryx flapped its wings but was not capable of long distance flight. Nor could it soar like birds of prey.

Instead, the feathered Jurassic creature probably made short bursts of ­limited low-level flight to escape danger, say experts in Grenoble, France, after X-ray analysis of fossil bones.

Pheasants fly in a similar way to avoid predators or human hunters.




Archaeopteryx – which means “ancient wing” – lived in the Late Jurassic period in what is now southern Germany.

The first fossil skeleton of one of the creatures, known as the London Specimen, was unearthed in 1861 near Langenaltheim and is housed at London’s Natural History Museum.

Similar in size to a magpie, it shared characteristics of Earth-bound dinosaurs and modern birds, including winged feathers, sharp teeth, three fingers with claws, and a long bony tail.

However despite being thought of as the first bird, experts now view Archeopteryx as a flying dinosaur.

Nor was it a direct ancestor of modern birds. Despite sharing a common dinosaur ancestor with birds, Archaeopteryx represents a “dead end” side branch on the evolutionary tree.

Present day birds are generally believed to have evolved from a group of small meat-eating dinosaurs known as maniraptoran theropods.

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See The Amazing Way A Beetle Survives After Being Eaten

The toad’s reaction to the explosion deep in its stomach is not instantaneous. But in time the body shakes, the mouth opens, and the culprit is expelled: a mucus-covered beetle that will live to fight another day.

Japanese scientists captured footage of the great escape during lab tests that pitted the walking powder kegs that are bombardier beetles against hungry toads of different species and sizes.

So effective were the beetle’s defences against being eaten alive that even the researchers were taken aback.

The escape behaviour surprised us,” said Shinji Sugiura, an agricultural scientist who performed the studies with Takuya Sato at Kobe University.

An explosion was audible inside several toads just after they swallowed the beetles.”

From a chemical standpoint, bombardier beetles are among the most unstable animals on the planet.




When threatened, they mix chemicals in their hindquarters, hydrogen peroxide and hydroquinones, to produce an explosion of searing benzoquinone irritant.

The boiling spray repels most predators the beetles encounter.

Sugiura and Sato wanted to know if the bombardier’s defences might help them survive being swallowed by the toads they encountered in the forests of central Japan.

To find out, they collected beetles, Japanese common toads, and Japanese stream toads, and filmed what happened when predator met prey.

The footage captured heroic feats of survival. The toads caught the bombardier beetles with lightning fast flicks of the tongue. But once ingested, the beetles detonated their toxic bombs.

At times, Sugiura said, the explosions made an audible “bu” sound inside the amphibians. Vomiting ensued.

The defence was not always effective though. Only 34.8% of common toads and 57.1% of stream toads vomited up the beetles, which all survived their encounter with the predator’s stomach juices.

The odds of survival favoured large beetles being gobbled by small toads, probably because the bigger beetles unleashed more devastating toxic explosions.

While some beetles were thrown up within 15 minutes, others remained in the toads’ stomachs for nearly two hours, the equivalent of a Jonah-esque three-day ordeal in human terms.

To check that the explosions were key to survival, the scientists disarmed a batch of beetles by triggering their sprays until the chemicals ran out, and then left them alone with toads.

Only 5% of those eaten were vomited up, according to a report in Biology Letters.

How some bombardiers lived for so long in the toads’ stomachs remains a mystery.

In tests, Sugiura found bombardier beetles had a better chance than other ground beetles of surviving for 20 minutes inside toads’ stomachs, perhaps because they are better protected against stomach acid.

The bombardier beetle species may have evolved a high tolerance for toads’ digestive juices,” he said.

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