News & Current Affairs

July 17, 2009

Tiny lizard falls like a feather

Filed under: Latest — Tags: , , , , , , , , , , , , — expressyoureself @ 6:07 pm
Tiny lizard falls like a feather

The lacertid lizard Holaspis guentheri

Not one to free fall

A tiny species of lizard is so light that it falls to the ground like a feather, scientists have discovered.

Outwardly, little of the animal’s body seems adapted to flying, gliding or moving through the air in any way.

But a slow-motion camera has revealed that when the lizard jumps from a height, it can slow the rate of its descent and land gently on the ground.

The lizard’s surprising aerial ability might help explain how some animals became true gliders.

Details of the little lizard’s talents are published in the Journal of Experimental Biology.

Controlled descent

Active flight, powered by the flapping of wings, has evolved in three living lineages of animals: birds, bats and insects.

But at least 30 different types of animal have evolved the ability to control their aerial descent, by parachuting or gliding to ground.

For example, gliding frogs use huge webbed feet, flying squirrels use long flaps of skin between their legs, and flying fish use their fins to glide.

Other animals have less obvious morphological adaptations.

Gliding snakes flatten and undulate their bodies, which helps to slow their fall while some species of ant are so tiny they can jump out of trees and freefall gently to lower on the trunk without hurting themselves.

So Bieke Vanhooydonck of the University of Antwerp became extremely interested when she read some old scientific papers reporting anecdotal evidence that a relatively ordinary species of lizard might also be able to glide from tree to tree.

Holaspis guentheri belongs to a group of lizards known as lacertids, which live in the Old World.

The lacertid lizard Holaspis guentheri

A slender, flat build helps

Though colourful, they do not stand out in terms of their behaviour, morphology or ecology.

“Also, compared to other gliding lizard species, it does not have any conspicuous morphological adaptations to an aerial lifestyle, ie no cutaneous flaps, webbed feet etc,” says Vanhooydonck.

“It made me very curious about whether these animals were really able to ‘glide’ and if so, how they were accomplishing it.”

Leaping platform

So Vanhooydonck and colleagues in Belgium and France filmed individual lizards leaping from a platform two metres above ground.

They compared the performance of H.guentheri with a rock-dwelling lizard (Podarcis muralis) that never takes to the air, and a highly specialised leaping gecko (Ptychozoon kuhli) that has a range of skin flaps that it uses to parachute to the ground.

For each, they examined the duration of each species’ descent, the horizontal distance it covered and at what speed.

Both the rock-dwelling lizard and H.guentheri landed 50 centimetres from the base of the platform, while the gecko landed up to 1m away. But H.guentheri fell for longer, and more slowly than its rock-dwelling competitor.

“Much to our surprise, H. guentheri is able to slow down its descent and has low impact forces upon landing,” says Vanhooydonck.

In fact, the lizard weighs just 1.5g, which is one third of the rock-dwelling lizard’s weight and one-tenth of the gecko’s.

Once weight was factored in, the researchers found that H.guentheri landed 20cm further away that it should have done had it fallen like a stone.

Leaping gecko (Ptychozoon kuhli)

The leaping gecko P. kuhli is a true glider

“Also its wing loading, the ratio of mass to surface area, is extremely low and in the same range as that of the gekko.”

However, the two species achieve this aerial ability in different ways. As a result of its webbed feet and body flaps, the gecko achieves a low wing loading by having a large surface area.

H. guentheri has a low wing loading too, but by being so light.

X-ray scans of the lizard’s body revealed its bones are packed full of air spaces.

Although the lizard’s light weight and ability to fall gently are linked, it is still unclear whether its air-filled bones are an adaptation for parachuting, or whether they evolved for another reason.

It is also unclear whether H.guentheri glides from tree to tree to escape predators or move about more efficiently.

“Because of [the lizards’] secretive lifestyle, it is very hard to observe them in the wild, but it seems plausible they use it as an escape response,” says Vanhooydonck.

And that could be just how other gliding animals took the first evolutionary steps towards an aerial lifestyle, she says.

Advertisements

August 30, 2008

New giant clam species discovered

New giant clam species discovered

Giant clam (M.Naumann)

The new giant clam species has a deeply folded shell outline

A new species of giant clam has been discovered in the Red Sea.

Fossils suggest that, about 125,000 years ago, the species Tridacna costata accounted for more than 80% of the area’s giant clams.

The species may now be critically endangered, researchers report in Current Biology journal.

The scientists believe their findings may represent one of the earliest examples of the over-exploitation of marine organisms by humans.

T. costatahas “very peculiar characteristics” that set it apart from two other species of giant clam that are also found in the area.

The Latin word costatus means “ribbed” and T. costata has a distinctive, zig-zag outline to its shell.

“The new species are mid-sized clams – up to 40cm long and a couple of kilograms heavy,” explained co-author Dr Claudio Richter, from the Alfred-Wegener Institute for Polar and Marine Research, Germany.

The new species has a distant relative, T. gigas, which can grow up to 1.4m long.

Live specimens of T. costata appear to be restricted to very shallow waters. Other species were also found in deeper reef zones.

The clam has an earlier and shorter breeding season that coincides with the seasonal plankton bloom. Genetic analysis confirmed the status of the new species.

‘Time travel’

“One of the great features of the desert-enclosed Red Sea is that you can literally time-travel from the present, several hundred thousand years into the past,” said Dr Richter.

The research team uncovered well-preserved fossil evidence that suggested stocks of these giant clams plummeted some 125,000 years ago – during an interval between Ice Ages.

They believe this period coincides with the appearance of modern humans in the Red Sea area.

Giant clams were abundant, large in size and easily accessible – making them an attractive food source for hunter-gatherers.

In “pre-human times”, T. costata may have been up to 60cm long. Since then, shell size has also decreased dramatically.

“The overall decline in giant clam stocks – with the striking loss of large specimens – is a smoking gun indicating over-harvesting,” said Dr Richter.

The scientists were not expecting to find a new species in an area as well studied as the Red Sea.

The research highlights how little is known about marine biodiversity in general, the scientists said.

“The coral reefs in particular… may still harbour very large surprises,” said Dr Richter.

August 28, 2008

For those too young to remember the Cold War…

For those too young to remember the Cold War…

WarGames

Before the days of flat screen monitors… and Perestroika

The conflict in Georgia has awoken fears of a new Cold War between Russia and its allies and the West, nearly 20 years after the fall of the Berlin Wall. But will the animosity come back to haunt Western imaginations as it once did?

“We share the same biology,
regardless of ideology.
Believe me when I say to you,
I hope the Russians love their children too”

That couplet might be a mere piece of lyrical doggerel to any listener born after 9 November 1989, but when Sting released the single Russians in 1985, it came out of a deep mine of anxiety in the West about the course of the Cold War.

Sting

A good period in which to make profound statements…

For nearly five decades, the Cold War provided a rich seam running right through popular culture in the West, throwing out films, music, novels and even computer games that carried the fears, conscious and subconscious, of millions.

In the 1950s, science fiction movies were often allegories about different aspects of Cold War politics. Invasion of the Body-Snatchers was interpreted as a reference to McCarthy-era paranoia, Invaders from Mars as a parable of communist infiltration, and the Day the Earth Stood Still as a simple fantasy that some higher supernatural power would come to try and sort everything out.

After the world reached the brink of war during the Cuban Missile Crisis in 1962, there was another wave of Cold War-inspired fiction, with Stanley Kubrick’s Dr Strangelove perhaps the most notable example.

With the detente of the 1970s the Cold War thread became less noticeable, but with worsening relations in the early 1980s, both sides of the Atlantic were suddenly replete with fictional Cold War dystopian scenarios.

On the British side people were treated to the agonisingly poignant graphic novel When the Wind Blows by Raymond Briggs and its film adaptation, as well as 1984’s Threads, about the terrifying aftermath of a nuclear strike. On the other side of the Atlantic, there were the mini-series Amerika and World War III, and the gruesome The Day After with its vivid montages of men, women, children and even horses being vaporized.

Frankie Goes to Hollywood

…and ripe for sensational scare-mongering

On the silver screen WarGames explored the issue of computer hacking against a background of mutually assured destruction , while Red Dawn took the usual brat pack characters complete with preppy letterman jackets, and armed them with AK-47s to fight a Soviet invasion of the US. Popular attitudes towards the Eastern Bloc were shaped by movies like Rocky IV, where the drug cheat Ivan Drago was emblematic of suspicions held against Soviet athletes.

As well as Sting’s Russians, Frankie Goes To Hollywood’s chart-topper Two Tribes provided a musical accompaniment to the era. It seems strange to discuss now what was, even then, viewed as often laughable ephemera, but the course of popular culture reflected deep-seated fears, particularly significant among those too young to temper their concerns with a grasp of the political context.

Almost as soon as it had intensified, the Cold War quickly ebbed away, and by the end of the 1989, with the Berlin Wall coming down and relations defrosting across the whole of eastern Europe, it suddenly became a bit silly to pick the Soviet state as baddies.

Hollywood had to find new protagonists for a new zeitgeist, and fast.

Bond sabbatical

While rarely casting Russia itself as the main enemy in a storyline, and indeed often featuring a sympathetic KGB general, the James Bond franchise was unmistakably driven by Cold War themes of espionage and fear of weapons technology. It was inevitably affected, says film critic James King.

It was a competition to be modern – consumer society was used as a bulwark against communism
Jane Pavitt

“Bond went into limbo for seven years, for many reasons, but one was that it didn’t feel relevant any more.

“The first film I remember that actually caught up was True Lies. When that came out it was almost a James Bond film and it had a new Hollywood enemy, which was an Arab – this was the new thing.”

Post 9/11 there has been a glut of movies either tackling the threat of terrorism, attacking the politics of the war on terror and Guantanamo Bay, as well as a host of television programmes that have explored the fall-out for Muslim communities on both sides of the Atlantic. A poster for the current movie Shoot on Sight – with its tag line “Is it a crime to be a Muslim?” – is typical.

In the space between the end of the Cold War and Islamist terrorism entering the mainstream mindset as the main threat to the West, movie producers did their best to come up with convincing action movie baddies.

Having been conceived long before the fall of the wall, the Hunt for Red October, an adaptation of Tom Clancy’s 1984 novel, still performed well at the box office in 1990. But in projects conceived after the end of Cold War hostilities, the baddies are very often neo-nationalists or rebels trying to destabilise a friendly Russia (Crimson Tide and Air Force One) or are avaricious terrorists and gangsters of other nationalities (Die Hard).

Cold War the Sequel

The effect of the end of the Cold War on secret services and military personnel came to be a major theme. John Le Carre was one of those spy novel authors who made the transition smoothly. The Russia House marked the last of his novels released during the Cold War, the next three deal with the effect of the thaw on intelligence operatives, while the subsequent four, including the Tailor of Panama and the Constant Gardener are not directly related to the Cold War. But Hodder and Stoughton, his publisher, maintain sales of the Cold War novels were unaffected by the events of 1989.

Threads

Threads – not your average prime-time BBC drama

King is sceptical about whether current Cold War fears will quickly feed back into popular culture.

“Films take a while to get on the screen – I don’t think we will see anything for a year.”

Film producers and publishers may also feel that with the long lead times, tensions could be defused by the time anything gets to market.

They are returning to Cold War classics but not necessarily because of modern fears over relations between the West and Russia. WarGames was recently remade as a straight-to-DVD release although terrorism underpinned the story rather than a renewed Cold War. It has also been recently reported that Red Dawn is to be remade, although the exact plot is unclear.

But as well as those cultural products directly referencing or making allusions to the Cold War, the conflict also provided the backdrop to massive shifts and vigorous battles in everything from product design and modern art to fashion, says Jane Pavitt, curator of the Cold War Modern exhibition opening next month at the Victoria and Albert Museum.

“It was a competition to be modern,” says Pavitt. “Consumer society was used as a bulwark against communism in Europe in the 1950s. That’s why fashion and kitchen goods can be seen as part of this.”

For those who were too young to remember the Berlin Wall coming down, or were born afterwards, the unique fears of the Cold War era, and the popular culture they steered, may be hard to appreciate.

But for anyone over the age of 25 in the West, they remain a deeply significant part of our psyche.


Add your comments on this story.

What about Soviet / Eastern Bloc popular culture during the cold war – was it also full of espionage dramas and ‘what if’ nuclear bomb scenarios? As someone old enough to remember it from a British perspective, I realise I have no idea at all how it was perceived and represented in media the other side of the Iron Curtain. I’m sure there is a level of propaganda and also aware that creativity was somewhat stifled, but is there a parallel strand of writing/drama/film-making that we’re all ignorant of over here?
WorldGirl, Enfield, UK

I have grown up at the other side of the Iron Curtain and can assure you: the fear that the Cold War would spiral out of control was just as real on our side, only that we expected the West to make the first move. This was reflected in our popular culture in a similar way as was quoted in the article. I used to think: perhaps both sides are just too afraid of each other, perhaps such fears could be calmed by assuring each other that “we” would not make the first move. However, my views have changed a bit over the years. Having seen how readily the West is prepared to enter into a war (Yugoslavia, twice in Iraq, Afghanistan) and how openly it encroaches on Russia’s borders by supporting various colour-coded revolutions, I am beginning to wonder who was indeed the more aggressive side. For anyone getting into a rage about this posting: just for one moment, try to forget our view that we are always right and that our view on democracy justifies any means to spread it around the world. Try to be unbiased and then read again what I said.
Holger Laux, Bristol, UK

It’s interesting, and perhaps significant, that in times of national perceived potential threat from outside, so much creativity happens. I remember vividly the tension of the 1980s, the big changes in the UK and around the world. In some ways, it was an exciting time because every new day could bring danger. Is that what we humans survive on and does it draw us together?
Krystyna, Sedgley

In the mid 1980’s I can remember being in a 6th form who generally agreed that they would not live to be 30 because nuclear war was both imminent and inevitable. A strange mix of living a normal life but with the constant knowledge of impending disaster. This is probably why I felt so uneasy with the worsening relationship between Russia and the West. The world is, in my opinion, much less stable than it was in the 80s and the politicians are much more dangerous and paranoid than Maggie/Ronnie/Andropov/Chernenko.
John Ferris, Coventry, UK

I’m 27 and can just about remember the Berlin Wall coming down, though I can’t say I remember much more about the cold war. I’d raise your threshold to at least 30!
James, London

How true. I was only nine years old when they installed an air raid siren to the roof of our school. There were lots of discussions about what we would do with our last three minutes of life before the bombs arrived. It sounds trivial now but at the time we were convinced it would happen.
Dawn, Redhill

Reading the above it confirms my gut feeling that it is the Media that stir up scenarios causing more trouble than most just by publishing half of the story and twisting the facts. Even the BBC has succumbed to the drum of the gutter press by allowing the papers to show headlines on some of their programmes such as Breakfast, the BBC does not need to give the like of these people air time they have enough journalists to concoct their own stories, so why of why do they (BBC) despoil their standards with drivel?
Robert, Liverpool

I was born in 1985 so missed the hysteria, but we were subjected to ‘Threads’ in school. I didn’t sleep for weeks and when I did I dreamt of that cat on fire and the melting milk bottles! Haven’t been to Sheffield since!!
Martin Doyle, St Albans

Threads was an excellent – and terrifying – story, and was also the first ‘post-holocaust drama’ to incorporate the concept of the nuclear winter, which had only recently been realised. And it was more than just a story: it included occasional subtitles to spell out what would be happening. It’s hardly likely to get repeated (and would in all likelihood be out of date with its figures), but as an illustration of why not to play with nuclear weapons it was second to none.
Ruaraidh Gillies, Wirral, UK

Please stop doing this. Drumming up panic when there is no need. Even Russia has said they don’t want another cold war. There is NO crisis, just sabre rattling as always.
Rich, UK

Yes a large influence on Culture of the 80’s when I grew up. I went into the RAF and ended up at Greenham Common on the other side from the peace camp. I have still have a Cold War playlist on my iPod with tracks like ‘Two Tribes’, ‘Mad World’ and ’19’. Recent Computer games like Operation Flashpoint also hark back to the Cold War 80s. Are we going into a Second Cold War. Yes and there is nothing the West can do.
Simon CS, Farnham, Surrey, UK

The Cold War was fun and inspired some great films.
Matt, Philadelphia USA

Let’s hope that we don’t go back to the scare-mongering of the early eighties. For once I would like to think that today’s youngsters are a bit de-sensitised to the whole ‘we’re all going to die’ thoughts portrayed back then. I myself started digging out a bunker at the age of seven for our family to shelter in. When I was discovered I claimed it was a copy of Percy Thrower’s Blue Peter sunken garden!!!
Jenny, Wolves

I remember being absolutely terrified of nuclear war growing up. It was an all too real possibility. The intro to “Two Tribes” used to frighten me, and “Threads” is just as disturbing to watch now as it ever was. We also had the misfortune to live nine miles from the RAF/US Navy bases and oil refineries making us a prime target. When the Air Force did their low-flying exercises in the middle of the night, I’d lie awake waiting for a bomb blast to follow. That said, I think the idea of being nuked at any moment really beefed up Western popular culture at the time.
Mandi, Cardiff, Wales

They don’t need to drop the bomb. Russia has between 1/4 and 1/3 of the world’s oil and natural gas.

All they have to do is turn the taps off.
Philip Le Roux, Aldershot HANTS UK

Create a free website or blog at WordPress.com.