What do a leaping lizard, a Velociraptor and a tiny robot at Bob Full’s laboratory have in common? They all use their tails to correct the angle of their bodies when they jump.

Thomas Libby filmed rainbow agamas – a beautiful species with the no-frills scientific name of Agama agama – as they leapt from a horizontal platform onto a vertical wall. Before they jumped, they first had to vault onto a small platform. If the platform was covered in sandpaper, which provided a good grip, the agama could angle its body perfectly. In slow motion, it looks like an arrow, launching from platform to wall in a smooth arc (below, left)

If the platform was covered in a slippery piece of card, the agama lost its footing and it leapt at the wrong angle. It ought to have face-planted into the wall, but Libby found that it used its long, slender tail to correct itself (below, right). If its nose was pointing down, the agama could tilt it back up by swinging its tail upwards.

(more…)

In flight, the hovering hummingbird is more like a insect than a bird. Most most birds only create lift when they flap downwards. But the hummingbird, by flipping its wing before it flaps upwards, can create lift in both directions. Insects do the same thing, but their wings have no bones inside them. How does the hummingbird fly like a fly despite having the bones of a bird?

Tyson Hedrick has found out, by filming hovering hummers with high-speed X-ray cameras. I’ve written about the results in my new piece for Nature News, so go there and read the full story (including details about how hummingbird muscles work at high gear). The meat of it is this:

By filming ruby-throated hummingbirds (Archilochus colubris) in flight, Hedrick showed that the birds invert their wings by twisting their wrists. “It looks like it’s affecting the whole wing because the bird’s skeleton is very compressed and its wrist isn’t very far from its shoulder,” says Hedrick.

In most birds, the wrist collapses on the upstroke to draw the wing towards the body as it is raised. Hummingbirds have adapted the same movements to rotate their wings instead. “The usual mechanism makes the upstroke aerodynamically invisible,” says Hedrick. “The hummingbirds’ mechanism makes the upstroke aerodynamically effective.”

The videos also showed that hummingbirds flap their wings by twisting the humerus (upper arm bone), rather than flapping it up and down from the shoulder like other birds. To understand the difference, Hedrick recommends trying to mimic a bird by flapping your arms. “You’re doing something not too different to what a seagull’s doing,” he says. To mimic a hummingbird, “hold your upper arm close to your body with your elbow on your hip, and flap your forearms back and forth”.

Go try it. You can look as stupid as I did when I was writing about the paper.

Photo by Joe Schneid

If it looks like a grasshopper, and jumps like a grasshopper, it might be a cockroach. Last year, Mike Picker from the University of Cape Town discovered a new species of cockroach (Saltoblattela montistabularis) that jumps about using unusually long legs.

Dubbed the “leaproach“, the insect was named one of the top ten new species of 2011. Picker actually found it in 2006 while searching for an unrelated species of fly. It is a close relative of that famous pest, the German cockroach, but its body is very different. Its hind legs are huge, and around 70 per cent of its movements consist of jumps and hops. That makes it unique; all the rest of the 4,000 or so cockroach species get around by scuttling. Only one prehistoric species, which lived in the Jurassic period, had the legs of a jumper.

(more…)

We’re in western America in the late Jurassic period, and a herd of Camarasaurus dinosaurs is on the move. It’s the dry season and the giants are running out of water. Fortunately, they know exactly where to find a drink: a range of volcanic highlands to the west. To quench their titanic thirst, they must head for the hills. Now, 150 million years later, Henry Fricke from Colorado College had discovered a way of reconstructing their migration.

Vast migrations are a common feature among modern animals, and it’s reasonable to think that some dinosaurs undertook similar treks. But how do you work out the routes of long-extinct animals, when you only know about the spot where they died? The answer, as with many aspects of dinosaur life, is to look at their skeletons. As well as revealing the shape and size of these beasts, dinosaur fossils can also hold a record of their travel plans.

(more…)

Imagine you’re living off the coast of California, and you want to get to sunny Florida. That sounds easy enough, but there are three big problems in this imaginary scenario. First, you are a snail, so crossing even a small distance takes a lot of time. Second, there is a continent in the way. Third, you are a sea snail so you are not adapted to crawling on land.

These problems seem insurmountable and yet snails have made the journey. Osamu Miura from the Smithsonian Tropical Research Institute has found that horn snails crossed from the Pacific to the Atlantic Ocean around 750,000 years ago, while other individuals made the opposite journey around 72,000 years ago. And they probably flew on bird airlines.

(more…)

Many birds sing to woo females, but some hummingbirds go to great lengths to do so. They climb to between 5 and 40 metres before plummeting past perched females in death-defying dives. They pull up at the last minute, spread their tail feathers and produce a loud chirpy song. The song comes not from the birds’ mouths, but from their tails. The splayed tail feathers vibrate as air rushes past them, causing them to flutter.

Flutter sounds colloquial and innocuous, but it can be deadly. It’s what happens when air, moving at just the right speed, zooms past objects with just the right stiffness, setting up large and potentially disastrous vibrations. Flutter brought down the passenger plane Braniff Airways Flight 542, killing everyone on board. Flutter wrecked the Tahoma Narrows Bridge, causing it to warp and twist like a piece of rope. But flutter also ensures that male hummingbirds get some action.

(more…)

In the Olympic Games of Ancient Greece, long-jumpers would leap while carrying weights called halteres in their hands. From either a standing start or a short run, they swung the weights and leapt as their arms came forward. The halteres each weighed up to nine kilograms, and would have added around 17 centimetres to a 3 metre jump. Olympians first used the hand weights in 708 BC, but other apes were jumping with a very similar technique millions of years earlier – gibbons.

Gibbons are undisputed masters of the treetops, best known for swinging around at unfeasible speeds from their long, powerful arms. Their wrists contain ball-and-socket joints, which allow their entire body to easily pivot about their hands. This style of movement, known as brachiation, is a gibbon speciality (see video below). But these apes are also accomplished jumpers. Field scientists have watched them clear gaps as large as 10 metres.

(more…)

---

The flying lemur must be one of the most inaccurately named animals in the world, for it cannot fly and it isn’t a lemur. This is why most biologists prefer to refer to it by its other name – the colugo. It lives in the forests of South-East Asia, where it glides (not flies) from tree to tree. From a standing start, it launches itself into the air with a powerful jump and spreads the massive membrane that runs from its chin to its hands, feet and tail.

The glide looks effortless, but Greg Byrnes from the University of California, Berkeley has found that it’s a surprisingly inefficient means of travel. Contrary to expectations, gliding actually takes up more energy than travelling the same distance by running and jumping through the canopy. So why do it? Byrnes has the answer – it saves time. For the busy modern colugo, gliding saves precious minutes that could be better spent on eating, mating or whatever it is that colugos do.

(more…)

Somewhere on the side of your thigh bone, there is a tiny hole. It’s called a “nutrient foramen”. An artery passes through this gap, suffusing the bone with blood and oxygen. The hole is found in all thigh bones, from those of birds to lizards, and it always fulfils the same function. But it can also double as a keyhole into the past, allowing us to peek at the lives of animals long extinct.

Roger Seymour from the University of Adelaide has used the size of these holes to show that many dinosaurs of all sizes led active lifestyles.

(more…)

The wings of bats provide them with support and lift as they fly. But they are also giant sensors that tell bats about the flow of air around their bodies, helping them to execute sharp manoeuvres without crashing.

The wings’ ability to monitor airflow depends on tiny hairs that cover their surfaces. The hairs were discovered almost a century ago. Scientists suggested that they are sense organs that allow bats to fly in complete darkness. That idea fell out of favour in the 1940s when Donald Griffin and Robert Galambos showed that bats navigate by listening for the echoes of their own calls. The discovery of bat sonar solved the mystery of their night-time aerobatics, and the wing hairs fell into obscurity.

But John Zook at Ohio University had not forgotten about them. He has shown that the pre-sonar theories were partly correct. The hairs complement a bat’s echolocation and turn it into a better flier, allowing the animal to “feel” its way through the sky.

(more…)