Fastest Wings on Earth Show Extremes of Sexual Selection

With feathers that resonate at precisely 1,500 hertz, the male club-winged manakin is perhaps the bird world’s most perfectly tuned example of sexual selection.

By pinning down the frequency, researchers have completed a long investigation into the bird’s sonic physiology and showed just how far some guys go to impress the ladies. According to scientists, the fundamental anatomy of the wings has been completely reworked to play a sound for courtship.

The early work focused on the anatomical peculiarities of the males’ wings. One odd middle feather has seven ridges, while an adjacent feather has an especially thick tip. A high-speed video recording of males making their trademark sounds showed they shake their wings 107 times per second. That’s faster than a hummingbird’s wingbeats, and faster than was even thought to be possible in a vertebrate.

The sound was replicated by putting feathers inside an apparatus that measured their acoustic resonance at high-speed vibrations. At 1,500 vibrations per second, and not a few more or less, the feathers’ resonance swelled.

That number is predicted by the feathers: seven ridge bumps, multiplied by two — the upstroke and downstroke — multiplied by 107 wingbeats per second equals a frequency of 1498 hertz, almost exactly what they measured in the lab.



Original article here.

Elephants Run Like No Other

A biomechanical analysis of running elephants has revealed that Earth’s largest land animals do some strange things at high speed.

Unlike every other quadruped, they use all four legs for braking and propulsion, rather than rather dividing those tasks between hind and front legs.

Elephants also prove to be extremely inefficient while running. Compared to animals like horses, they perform quite poorly.

Scientists videotaped six Asian elephants as they ran across mechanical plates that measured the force of each stride. By combining gait models distilled from the video with force measurements, they could quantify the elephants’ biomechanics.

Surprisingly, they learned that braking and propulsion is performed equally by each leg. In other quadrupeds, rear legs are mostly used to push off, and front legs to slow down. The elephants’ arrangement likely makes them more stable and reduces physical stress placed on each leg.

Original article here.

Monkey Walks Upright

A 5 year-old monkey in a zoo in Jerusalem has astonished zookeepers by walking upright:

All-Black Penguin Discovered

The above melanistic penguin was discovered at Fortuna Bay on the subantarctic island of South Georgia.

Melanism is merely the dark pigmentation of skin, fur--or in this case, feathers. The unique trait derives from increased melanin in the body. Genes may play a role, but so might other factors. While melanism is common in many different animal species, the trait is extremely rare in penguins. All-black penguins are so rare there is practically no research on the subject--biologists guess that perhaps one in every quarter million of penguins shows evidence of at least partial melanism, whereas the penguin above appears to be almost entirely melanistic.

The penguin did not appear to exhibit different behavior than that of his fellow penguins, and he seemed to mix well with them.

Original article here.

Redwood Perspective

Click on the below image to see a size perspective of a giant redwood. Be sure to click again on the image to zoom out (your browser will likely shrink it initially to fit the screen).