How a flamingo balances on one leg

Some of the built-in tricks for extreme bird balancers work without muscle effort.

A question flamingo researchers get asked all the time — why the birds stand on one leg — may need rethinking. The bigger puzzle may be why flamingos bother standing on two. Balance aids built into the birds’ basic anatomy allow for a one-legged stance that demands little muscular effort, tests find. This stance is so exquisitely stable that a bird sways less to keep itself upright when it appears to be dozing than when it’s alert with eyes open, two Atlanta neuromechanists report May 24 in Biology Letters.
“Most of us aren’t aware that we’re moving around all the time,” says Lena Ting of Emory University, who measures what’s called postural sway in standing people as well as in animals. Just keeping the human body vertical demands constant sensing and muscular correction for wavering.  Even standing robots “are expending quite a bit of energy,” she says. That could have been the case for flamingos, she points out, since effort isn’t always visible.

Hidden hip

Translate that improbably long flamingo leg into human terms, and the visible part of the leg would be just the shin down. A flamingo’s hip and knee lie inside the bird’s body.

Ting and Young-Hui Chang of the Georgia Institute of Technology tested balance in fluffy young Chilean flamingos coaxed onto a platform attached to an instrument that measures how much they sway. Keepers at Zoo Atlanta hand-rearing the test subjects let researchers visit after feeding time in hopes of catching youngsters inclined toward a nap — on one leg on a machine. “Patience,” Ting says, was the key to any success in this experiment.
As a flamingo standing on one foot  shifted to preen a feather or joust with a neighbor, the instrument tracked wobbles in the foot’s center of pressure, the spot where the bird’s weight focused. When a bird tucked its head onto its pillowy back and shut its eyes, the center of pressure made smaller adjustments (within a radius of 3.2 millimeters on average, compared with 5.1 millimeters when active).

Museum bones revealed features of the skeleton that might enhance stability, but bones alone didn’t tell the researchers enough. Deceased Caribbean flamingos a zoo donated to science gave a better view. “The ‘ah-ha!’ moment was when I said, ‘Wait, let’s look at it in a vertical position,’” Ting remembers. All of a sudden, the bird specimen settled naturally into one-legged lollipop alignment.
In flamingo anatomy, the hip and the knee lie well up inside the body. What bends in the middle of the long flamingo leg is not a knee but an ankle (which explains why to human eyes a walking flamingo’s leg joint bends the wrong way). The bones themselves don’t seem to have a strict on-off locking mechanism, though Ting has observed bony crests, double sockets and other features that could facilitate stable standing.
The bird’s distribution of weight, however, looked important for one-footed balance. The flamingo’s center of gravity was close to the inner knee where bones started to form the long column to the ground, giving the precarious-looking position remarkable stability. The specimen’s body wasn’t as stable on two legs, the researchers found.

Reinhold Necker of Ruhr University in Bochum, Germany, is cautious about calling one-legged stances an energy saver. “The authors do not consider the retracted leg,” says Necker, who has studied flamingos. Keeping that leg retracted could take some energy, even if easy balancing saves some, he proposes.
The new study takes an important step toward understanding how flamingos stand on one leg, but doesn’t explain why, comments Matthew Anderson, a comparative psychologist at St. Joseph’s University in Philadelphia. He’s found that more flamingos rest one-legged when temperatures drop, so he proposes that keeping warm might have something to do with it. The persistent flamingo question still stands.

Microbes survived inside giant cave crystals for up to 50,000 years

Extremophiles hint at possible resilience of life beyond Earth

BOSTON — Microbes found stowed inside giant crystals in caves in Chihuahua, Mexico, may have survived there for tens of thousands of years. The microorganisms, which appear to be vastly different from nearly all life-forms found on Earth, offer a good indication of how resilient life can be in extremely harsh environments, including those found on other planets.
“These organisms are so extraordinary,” astrobiologist Penelope Boston said February 17 during a news conference at the annual meeting of the American Association for the Advancement of Science. They are not close to any known genus scientists have been able to identify, said Boston, director of the NASA Astrobiology Institute in Moffett Field, Calif. Their closest relatives live in caves halfway around the world or in volcanic soils or thrive on compounds such as toluene.

For eight years, Boston and her colleagues have been studying microbes deep inside the Naica lead, silver and zinc mine. Some microorganisms were discovered trapped in fluid pockets inside massive crystals of calcium sulfate. Analysis suggests that the microbes may have been tucked away in these tiny time capsules for 10,000 to 50,000 years and may have been dormant for some or all of that time. But they “remained viable in some fashion and were able to be regrown,” she said. Her team reawakened the microbes in the lab and studied their genetic material, along with genetic material from other organisms found in the walls of the cave and other areas near the crystals.
The microbes found inside the crystals appear to be similar but not identical to those living outside, on the cave walls and other nearby areas, Boston said. That leaves Boston and her team fairly confident that the samples were not contaminated with other microbes and that their age estimates for the crystal-trapped microbes is solid. The team has not yet published the result. If confirmed, the microbes would represent some of the toughest extremophiles on the planet — dwelling at depths 100 to 400 meters below Earth’s surface and enduring temperatures of 45° to 65° Celsius.
“Any extremophile system that we’re studying actually allows us to push the envelope of life further,” Boston said. “We add it to this atlas of possibilities that we can apply to different planetary settings.”
Studies like these show that some microbes are hardy creatures, willing to turn just about any habitat into a home. That’s promising for the hunt for life beyond Earth. It’s problematic, however, as researchers start to think about sending probes to potentially habitable worlds, such as Jupiter’s moon Europa and Saturn’s moon Enceladus. Boston’s discovery is a reminder of how little scientists know about the microbes on Earth. And that means there are unknowns about what life-forms could stow away on spacecraft sent to other worlds, says Cassie Conley, NASA’s planetary protection officer.
“If you took some of these organisms from Earth and put them elsewhere, they may do just fine,” she says. That’s not so great for studying any native life that might be there. The Earth-based life could take over and contaminate those worlds.