If its jaws were legs, this ant would leave a racehorse in the dust
News and notes about science
The Dracula ant is not much of a traveler. Located mostly in the tropics of Africa, Australia and Asia, the tiny creatures spend most of their lives burrowed into tree trunks or underground, to the endless frustration of scientists who would like to study them.
So, imagine the surprise of the researchers who recently discovered that Dracula ants might be the fastest animals on earth.
To be clear, you could easily beat the Dracula ant in a foot race. But one species, mystrium camillae, has a pair of ingeniously designed mandibles that can snap at 200 mph, according to a study published recently in Royal Society Open Science. That’s 5,000 times faster than you can blink your eye. It’s also three times faster than the mandibles of the trap-jaw ant, the previous fastest-moving insect on record.
The findings provide new insight into ant evolution and could help engineers design more powerful and efficient machines.
Frederick Larabee, an entomologist at the Smithsonian Natural History Museum, had been studying ants with powerful jaws at the University of Illinois in 2014 when his colleague, Andrew Suarez, was lucky enough to collect two colonies of Dracula ants in Borneo.
“We had spent four or five years trying to get a single colony,” containing thousands of insects, Larabee said. “But we were never able to get more than a few workers.”
Once Suarez brought the colonies back to his Illinois lab, the researchers quickly realized that their equipment was not powerful enough to study them.
They transported the ants to Duke University, where they could film them with a camera that captured up to 1 million frames per second. They also used X-ray imaging to study the mandibles in three dimensions.
They found that unlike trapjaw ants, whose jaws snap close from an open position, this Dracula ant uses its mandibles much like a pair of snapping fingers. The ant presses two small appendages together, spring loading them with potential energy, until one slides past the other. The immense force generated by the pent-up energy can be used to stun or kill prey, which are then brought back to the nest and eaten. It takes just 0.000015 seconds for the appendages to accelerate from 0 to 200 mph.
— Douglas Quenqua
Seeking clues to longevity in genes of Lonesome George
When Lonesome George, the only survivor of the Pinta Island tortoises of the Galápagos, died in 2012, the news landed with a blow.
He had lived for a century or more, a common life expectancy for giant tortoises, and all attempts to mate him during his last few decades were unsuccessful.
Recently, a team of scientists researching longevity turned to George for help in this search, mining his genetic code for clues to his long life span.
In a paper published recently in Nature Ecology & Evolution, the researchers reported preliminary findings of gene variants in George linked with a robust immune system, efficient DNA repair and resistance to cancer. The study also sets the stage for understanding giant tortoises’ evolutionary past, which might help to conserve them in the future.
Giant tortoises helped launch the theory of evolution. When Charles Darwin visited the Galápagos, he noticed the tortoises’ shell shapes were unique adaptations to their environments. He hypothesized that natural selection was at work.
The Galápagos tortoises have since continued to be a rich source of inquiry for evolutionary scientists. Adalgisa “Gisella” Caccone, a researcher at Yale University, has spent decades studying the reptiles that are the size of upright pianos.
But years ago, Caccone hit a wall — she needed someone to help her decipher which parts of the tortoises’ DNA were functional genes, which regions were not and what the genes’ functions might be.
She received a fateful message from Carlos López-otín, a professor at the University of Oviedo in Spain who has built a career studying cancer and aging in humans.
The scientists sequenced the entire genome of Lonesome George, plus that of an Aldabra giant tortoise from the Seychelles, another extraordinarily long-lived species.
The researchers then compared the tortoise genomes with those of mammals, fish, birds and other reptiles, looking for discrepancies that could affect aging. The scientists found evidence that a mutation in a gene called IGF1R, which has been linked with longevity in humans and mice, might contribute to the tortoises’ exceptional life span.
They also discovered that the tortoises had more copies of genes related to energy regulation, DNA repair, tumor suppression and immune defense compared with other creatures.
Generally, having many copies of genes can allow existing functions to occur more efficiently, or provide fuel for the evolution of new functions. — Steph Yin
Wolves surprise researchers by putting fish on the menu
Wolves are thought of as redmeat eaters, but a team of biologists in northern Minnesota, near Voyageurs National Park, has documented a pack that often enjoys a meal of fish.
It is a rare glimpse of wolves catching and eating freshwater fish, although they have been observed eating spawning salmon along the coast of British Columbia and Alaska. The discovery was recently published in the journal Mammalian Biology.
Wolves in Yellowstone have been known to chow down on trout, but it is unclear whether they actually caught the fish or if the catch was already dead.
“It is exceedingly rare, but they do it,” said Douglas Smith, the park’s wolf biologist.
Wolves were collared by the Voyageurs Wolf Project for research into pack territory and prey, primarily beaver but also deer fawns and moose calves. If wolves spent more than 20 minutes without moving, researchers went to the site to see if they were eating and, if so, what it was.
Tom Gable, a doctoral student working on the project, noticed from GPS data that wolves from a pack named Bowman’s Bay were spending a lot of time near a stream. He made a trek into the forest to see why.
When he arrived, he found a wolf on the bank of the stream.
“When I saw it, just 8 meters away, it was running full-steam into the middle of the creek, and then it ran back out,” he said. Gable saw the wolf crunching fish parts, and later found wolf tracks intermingled with fish remnants along the creek.
Researchers set up remote cameras on that section of creek and discovered the techniques a wolf uses to capture aquatic prey.
“The wolves are standing next to the creek in the dark, just listening or looking,” Gable said. “You can see the wolves abruptly head to the water several times after hearing a splash — they learned what a fish splashing in the creek sounds like and they know that it means food. Incredible.”
The researchers have compiled GPS data from seven packs in the area, but this is the only one that appears to fish.
— Jim Robbins
The little plant that survives inside a duck
Duckweeds are humble-looking plants whose tiny, brilliant green globules spangle ponds all over the world. Some duckweeds are the smallest flowering plants in nature.
Scientists working in Brazil have just discovered that one duckweed, Wolffia columbiana, has a surprising talent. In Biology Letters, the authors reported recently that this duckweed can likely hop entirely intact from wetland to wetland by hitching a ride in the feces of birds.
Duckweeds can reproduce by copying themselves, so if one duckweed lands where a duck relieves itself, it is capable of eventually creating a dense mat of duckweeds where there were none before. Understanding how this little plant travels may help scientists develop strategies for containing forms of duckweed that have become invasive species in some environments.
To study how ducks and geese might be spreading seeds or pieces of plants between bodies of water, graduate student Giliandro Silva at the Universidade do Vale do Rio dos Sinos in southern Brazil had been collecting and freezing their feces to examine later on. However, when he took a look inside, he was shocked to see the globules of whole duckweed plants, intact after having been swallowed and passing through the birds’ digestive systems.
Another sampling run to get fresh, unfrozen duck feces allowed Silva and his colleagues to test whether the plants were alive. They placed duckweeds salvaged from three separate birds’ feces in Petri dishes and waited to see whether they would grow.
The duckweeds soon began to replicate themselves. Seven duckweed globules were soon discovered in one dish where only one had been before, leading the scientists to conclude that they were unharmed by the corrosive acids of the birds’ stomachs and perfectly able to grow. That means that researchers and conservation groups interested in how this duckweed spreads in its native environment and in places where it is an invader will have to take into account this unexpected mode of travel.
— Veronique Greenwood
Thumbing a ride, without any thumbs
A spring-green aphid clambers over a clot of soil, busily making its way to the shelter of a forest of plants in the distance. The insect’s long legs help it lever itself over the uneven ground at surprising speed, but if you look closely at its back, you’ll see that it has a passenger: A tiny juvenile aphid, or nymph, is riding the adult cowboy-style.
This behavior, which scientists described for the first time recently in Frontiers in Zoology, results in the young one reaching the safety of a host plant much faster than it could on its own small legs. But the tactic is unpopular with the adults, who do not appreciate carrying a hitchhiker.
Aphids generally prefer to stay in their airy roosts among the foliage of their host plants, said ecologists Moshe Gish and Moshe Inbar of the University of Haifa in Israel, the paper’s authors.
The insects drop to the ground mainly when they sense serious, unavoidable danger.
Once they hit the ground, they are vulnerable to other predators, and so they rush to make it to a new host. While studying this behavior, the researchers noticed the peculiar sight of the young riding their elders.
To study the strategy more closely, they arranged a bare patch of earth surrounded by a ring of plants. Then, they held a potted plant bearing a thriving colony of aphids over the arena, shook it gently, and exhaled on it, prompting the insects to drop.
Many nymphs headed straight for adults and tried to climb aboard. When they clung to the adults’ legs or lower back, the adults shook them off, or tried to. The cowboy riding position, with the nymph centered on the adult’s upper back, seemed to be a sort of compromise.
“That was actually the least irritating position for the adult,” Gish said.
The senior aphids wasted time trying to get the young off as the nymphs crawled on their antennas and limbs, but once a nymph got all the way up into that spot, an adult was likely to cut its losses and just start moving toward the plants.
Rider nymphs reached safety about four times faster than nymphs walking on their own, suggesting that the behavior aids in their survival. Adults bearing a nymph, once they actually started walking, were no slower than adults without passengers.
— Veronique Greenwood