Feuer Frei!
07-13-11, 10:06 PM
Yea yea, i could have posted all this in my random facts thread for the next couple of weeks but thought this deserves it's own thread.
If you are a nature freak, like me, you might find this a good read:
Penguins can’t fly. But they can get airborne.
In fact, taking to the air, for even a brief instant, is actually a vital strategy penguins employ to avoid being eating by predators such as leopard seals (http://www.bbc.co.uk/nature/life/Leopard_Seal) or orcas (http://www.bbc.co.uk/nature/life/Killer_whale).
Now scientists have worked out the secret technique that penguins use to get airborne. It involves wrapping their bodies in a cloak of air bubbles – and it turns out to be the same technique that engineers use to speed the movement of ships and torpedoes through water.
Due to their body shape, and poor climbing ability, it is difficult for penguins to haul themselves ashore, especially onto rocky shorelines. And it can be almost impossible for a penguin to haul itself out from the ocean onto sea ice.
http://www.bbc.co.uk/blogs/wondermonkey/assets_c/2011/07/bubbles_two_penguins-thumb-996x572-77496.jpg
Image courtesy of Blue Planet, BBC.
So penguins leap ashore: they swim at speed to the surface, burst through and briefly get airborne to clear the rocks or ice shelf, and land on their breast.
Smaller species, such as Adelie penguins (http://www.bbc.co.uk/nature/life/Adelie_Penguin), can leap 2-3 metres out of the water, landing unscathed onto broken rock. Bigger species, such as Emperor penguins (http://www.bbc.co.uk/nature/life/Emperor_Penguin) (the largest of all), reach heights of 20 – 45 cm, but that is enough for them to leap out of holes in the ice and clear the ice’s edge.
But one aspect of this leaping behaviour has long puzzled biologists. As the birds swim toward the surface, they trail a wake of bubbles behind them. No one knew where these bubbles come from, or why there are there.
(Watch how Emperor penguins first evade a leopard seal, then when the coast is clear, they trail a wake of bubbles before leaping from the water, VIDEO IN SOURCE LINK AT BOTTOM)
The scientists slowed down this footage, analysing the speeds and angles of emperor penguins exiting the water, developing a basic biomechanical model of what was going on.
During this analysis, the researchers made some interesting discoveries. The bubbles of air being trailed by the penguins weren’t coming out of the birds’ lungs via the beak.
Instead, they were coming from the birds’ feathers.
“We were amazed to find that,” Professor Davenport tells me.
The researchers also realised that these air bubbles form a “coat” around the birds’ bodies as they rocket toward the surface at speeds of 19km an hour.
The “coat of air bubbles” first noticed on the Blue Planet footage is indeed what enables the penguins to get air as they leap onto land. Penguins have great control over their plumage, Professor Davenport tells me.
They raise their feathers to fill their plumage with air, then dive underwater. As the birds descend, the water pressure increases, decreasing the volume of the trapped air. At a depth of 15-20 metres, for example, the air volume has shrunk by up to 75%.
The birds now depress their feathers, locking them around the new, reduced air volume.
The penguin then swims vertically up as fast as it can, and the air in the plumage expands and pours through the feathers.
“Because the feathers are very complex, the pores through which the air emerges are very small so the bubbles are initially tiny. They coat the outer feather surface.”
Crucially, this coat of small air bubbles acts as a lubricant, drastically reducing drag, enabling the penguins to reach lift-off speeds.
This air insulation effect is known to boat architects and engineers. By placing a layer of air around a ship’s hull, or torpedo, for example, designers can dramatically reduce drag, and speed up the boat or weapon’s passage through the water as a result.
The penguins also appear to have overcome one other issue that blights naval architects trying to exploit “air lubrication” underwater.
http://www.bbc.co.uk/blogs/wondermonkey/assets_c/2011/07/bubbles_single_penguin-thumb-995x573-77498.jpg
The moment before liftoff. Image courtesy of Blue Planet, BBC.
Although a coat of tiny bubbles dramatically reduces drag, it can also have a major slowing effect if the bubbles reach a ship or torpedo’s propeller. That’s because the propeller starts pushing against air not water.
However, a penguin’s flippers, its means of propulsion equivalent to the propeller, are held outside of the bubble clouds, so they are not affected.
SOURCE (http://www.bbc.co.uk/blogs/wondermonkey/2011/07/penguins-take-to-the-air.shtml)
Pretty awesome. :up:
(http://www.bbc.co.uk/blogs/wondermonkey/2011/07/penguins-take-to-the-air.shtml)
If you are a nature freak, like me, you might find this a good read:
Penguins can’t fly. But they can get airborne.
In fact, taking to the air, for even a brief instant, is actually a vital strategy penguins employ to avoid being eating by predators such as leopard seals (http://www.bbc.co.uk/nature/life/Leopard_Seal) or orcas (http://www.bbc.co.uk/nature/life/Killer_whale).
Now scientists have worked out the secret technique that penguins use to get airborne. It involves wrapping their bodies in a cloak of air bubbles – and it turns out to be the same technique that engineers use to speed the movement of ships and torpedoes through water.
Due to their body shape, and poor climbing ability, it is difficult for penguins to haul themselves ashore, especially onto rocky shorelines. And it can be almost impossible for a penguin to haul itself out from the ocean onto sea ice.
http://www.bbc.co.uk/blogs/wondermonkey/assets_c/2011/07/bubbles_two_penguins-thumb-996x572-77496.jpg
Image courtesy of Blue Planet, BBC.
So penguins leap ashore: they swim at speed to the surface, burst through and briefly get airborne to clear the rocks or ice shelf, and land on their breast.
Smaller species, such as Adelie penguins (http://www.bbc.co.uk/nature/life/Adelie_Penguin), can leap 2-3 metres out of the water, landing unscathed onto broken rock. Bigger species, such as Emperor penguins (http://www.bbc.co.uk/nature/life/Emperor_Penguin) (the largest of all), reach heights of 20 – 45 cm, but that is enough for them to leap out of holes in the ice and clear the ice’s edge.
But one aspect of this leaping behaviour has long puzzled biologists. As the birds swim toward the surface, they trail a wake of bubbles behind them. No one knew where these bubbles come from, or why there are there.
(Watch how Emperor penguins first evade a leopard seal, then when the coast is clear, they trail a wake of bubbles before leaping from the water, VIDEO IN SOURCE LINK AT BOTTOM)
The scientists slowed down this footage, analysing the speeds and angles of emperor penguins exiting the water, developing a basic biomechanical model of what was going on.
During this analysis, the researchers made some interesting discoveries. The bubbles of air being trailed by the penguins weren’t coming out of the birds’ lungs via the beak.
Instead, they were coming from the birds’ feathers.
“We were amazed to find that,” Professor Davenport tells me.
The researchers also realised that these air bubbles form a “coat” around the birds’ bodies as they rocket toward the surface at speeds of 19km an hour.
The “coat of air bubbles” first noticed on the Blue Planet footage is indeed what enables the penguins to get air as they leap onto land. Penguins have great control over their plumage, Professor Davenport tells me.
They raise their feathers to fill their plumage with air, then dive underwater. As the birds descend, the water pressure increases, decreasing the volume of the trapped air. At a depth of 15-20 metres, for example, the air volume has shrunk by up to 75%.
The birds now depress their feathers, locking them around the new, reduced air volume.
The penguin then swims vertically up as fast as it can, and the air in the plumage expands and pours through the feathers.
“Because the feathers are very complex, the pores through which the air emerges are very small so the bubbles are initially tiny. They coat the outer feather surface.”
Crucially, this coat of small air bubbles acts as a lubricant, drastically reducing drag, enabling the penguins to reach lift-off speeds.
This air insulation effect is known to boat architects and engineers. By placing a layer of air around a ship’s hull, or torpedo, for example, designers can dramatically reduce drag, and speed up the boat or weapon’s passage through the water as a result.
The penguins also appear to have overcome one other issue that blights naval architects trying to exploit “air lubrication” underwater.
http://www.bbc.co.uk/blogs/wondermonkey/assets_c/2011/07/bubbles_single_penguin-thumb-995x573-77498.jpg
The moment before liftoff. Image courtesy of Blue Planet, BBC.
Although a coat of tiny bubbles dramatically reduces drag, it can also have a major slowing effect if the bubbles reach a ship or torpedo’s propeller. That’s because the propeller starts pushing against air not water.
However, a penguin’s flippers, its means of propulsion equivalent to the propeller, are held outside of the bubble clouds, so they are not affected.
SOURCE (http://www.bbc.co.uk/blogs/wondermonkey/2011/07/penguins-take-to-the-air.shtml)
Pretty awesome. :up:
(http://www.bbc.co.uk/blogs/wondermonkey/2011/07/penguins-take-to-the-air.shtml)