A bird is able to make drops of water defy gravity and flow into its mouth.
A team of MIT mathematicians and engineers has shown that some shorebirds use their long, thin beaks in a tweezering motion to make prey-bearing water droplets rise upwards so they can be consumed.
The work is even more remarkable because last year a team at the University of Bristol, led by Prof Jens Eggers, thought that it was the first to make droplets flow up a slope, by vigorously vibrating the droplets, and announced the feat in the prestigious journal Physical Review Letters.
But now it seems that birds beat them to this gravity defying feat, probably by millions of years.
As Charles Darwin showed nearly 150 years ago, bird beaks are exquisitely adapted to the birds’ feeding strategy.
In this case the north American phalarope takes advantage of surface interactions between its beak and water droplets to propel bits of food from the tip of its long beak to its mouth, the team reports in Science.
Wildlife biologists have long noted the unusual feeding behaviour of phalaropes, which spin in circles on the water, creating a vortex that sweeps small crustaceans up to the surface, just like tea leaves in a swirling tea cup.
The birds peck at the surface, picking up tiny droplets of water with their prey trapped inside.
Since the birds point their beaks downward, gravity must be overcome to get those droplets from the tip of the bird’s long beak to its mouth.
Until now, scientists have been puzzled as to how that happens.
To unravel the mystery, Prof John Bush and colleagues built a mechanical model of the phalarope beak that allowed them to study the process in slow motion.
As the beak scissors open and shut, each movement propels the water droplet one step closer to the bird’s mouth.
In this stepwise ratcheting fashion, the drop travels along the beak at a speed of about 1 meter per second.
The mechanism depends on the chemical properties of the liquid involved, so phalaropes and about 20 other birds species that use this mechanism are extremely sensitive to anything that contaminates the water surface, especially detergents or oil.
“Some species rely exclusively on this feeding mechanism, and so are extremely vulnerable to oil spills,” said Prof Bush.
This gravity-defying action is made possible by the surface tension of water, as well as a physical effect known as “contact angle hysteresis,” which normally causes drops to stick to solids.
When combined with the tweezering motion of the beak, however, this effect enables the water droplets to rise mouthward, explained Prof Bush.
Scraps of protein from the bones of a 68 million-year-old dinosaur and a mastodon carcass confirm their places in the family tree of life on Earth, researchers reported on Thursday.
The same team that established Tyrannosaurus rex is a distant relative of chickens filled in more gaps, showing that the dinosaur was far more closely related to living birds than to alligators.
And a 500,000-year-old mastodon is clearly a close relative of elephants, John Asara and colleagues at Beth Israel Deaconess Medical Center and Harvard Medical School in Boston reported.
They said their analysis of the ancient preserved proteins can be used to fill in all sorts of gaps in the tree of evolution. But it also shows that classical methods, based on studying an animal’s bones and other physical structures, are accurate.
“If you … just use molecular data, you can come to the same conclusion,” Asara said in a telephone interview.
Asara’s team used collagen taken from a remarkable find — the leg bone of a T. rex sealed in stone and broken when researchers had no other way of removing it.
Mary Schweitzer of North Carolina State University was able to get soft tissue and then protein out of the bone in 2005 — something previously considered impossible. She also got protein out of the much younger mastodon bone.
Asara’s team looked at the protein on a molecular level and designed a computer program to analyze it. A year ago, they established that the Tyrannosaurus was related to modern chickens and ostriches and that the mastodon was related to living mammals.
T. REX AND BIRDS
Now, reporting in the journal Science, they said they have established that the dinosaur is more similar to birds than to alligators or other reptiles such as anole lizards.
“Last year we just made a very loose connection based on (protein) sequence identification and we had no reptiles,” Asara said. “And now with very high probability we can make the connection of T. rex to birds.”
The mastodon “groups very nicely with elephants,” he said. “We can get a very nice tree.”
Some of the computer programs take days to run, Asara noted. But they will keep seeking fresh samples from paleontologists.
“You can’t just grab things from museums,” Asara said, because the protein in them will have degraded.
Last September, a researcher at Pennsylvania State University reported his team had pulled DNA from the hair shafts of Siberian woolly mammoths that were 50,000 years old.
Separately on Thursday, scientists at the University of California, Berkeley said they had used new rock dating methods to pinpoint the extinction of the dinosaurs more precisely than ever before.
Their improved argon-argon dating method places the Cretaceous-Tertiary, or K/T, boundary at 65.95 million years ago, give or take 40,000 years. Earlier estimates had put it at 65.5 million years ago, with a 300,000-year margin of error.
Do the tons of human-provided feed available warp birds’ ecosystems
If you feed the neighborhood stray cat, he’ll keep coming back. He’ll remember your house as an easy source of food and won’t have to scavenge for as much garbage or chase down as many field mice. The same thing obviously applies to birds and bird feeders, just on a much larger scale. At that point—when hundreds of thousands, even millions of feeders are involved—what kind of effect does the feeding have on the animals’ natural ecosystem? That’s the question Gillian Robb and her team at Queen’s University Belfast in the U.K. set out to answer through an experiment of their own and a review of the existing literature.
As you might assume, birds receiving extra food fared better than their counterparts over the winter, mated earlier, and had more offspring. The downside appeared in one of the review studies in which a variety of jay was shown to have laid its eggs too early when the bird had eaten an abundance over the winter. Its chicks were then born before spring food was available. Another negative impact was observed not in the well-fed birds, but in the migrating species who return seasonally and have to compete with those animals who have over-wintered with great success.
So far, nobody’s calling for a nation-wide dumping of backyard feeders. The researchers admit that the work is incomplete and preliminary and that they are far from understanding the issue completely.
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