英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—15

Thankfully the bear's appetite takes to the bigger prize. Tonight, they both get a share of the spoils. Late August, and as summer slides into autumn, the land around Baikal begins its transformation. Soft and rotting wood sprouts fast-growing fungus

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—14

But hot tempers on a hot rock beats being on the outside trying to get in. This exclusive resort, isnt accepting new guests. Come evening, a cool mist hangs over the lake, as the last of the egg-laying caddis flies get picked off by ducks and bears.

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—16

Chipmunks aren't the top collectors of the forest. That prize probably belongs to the colonies of red ants. Worldwide, ants are so numerous their total weight is almost as much as the human population, a force to reckon with. Workers form a never-end

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—13

Eighteen million years ago, it arrived in warm, tropical waters. Only then could the world's greatest reef be born. Australia's epic journey may have created perfect conditions for coral, but it also put it in the line of fire of the most powerful st

英语听力：自然百科 地球力场 Earth's Force Field—2

Radiation causes damage at the most fundamental level. It mutates the blueprint of life, DNA. Earth's magnetosphere is our crucial defense. It's so fundamental to our evolution and continued existence that the race is on to understand why it's changi

英语听力：自然百科 地球力场 Earth's Force Field—1

The solar system is a hostile place. Earth is under attack from deadly cosmic radiation. Life here is only possible, because it's protected by the magnetosphere, an invisible force field that cocoons the planet. But new evidence reveals that this vit

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—18

It's an astounding mechanism, but it looks like it's being overwhelmed. Recently, the coral has been telling us that its had enough. Because when it overheats, it self-destructs, expelling the algae that live with them. They turn deathly pale, a proc

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—17

One of the early methods to getting rid of a starfish was to cut them in half, then killing them with a knife, but starfish has this amazing property when they regenerate. Far from killing them, cutting these animals in half actually creates two of t

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—16

The pearl luggers then turned their attention to something else, a much bigger target. The reef has always provided a great haven for large animals, like turtles who nest on the coral piece. Whole populations of turtles were brought to the verge of e

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—15

Today, the elements that support the reef are in fine balance--sun, wind and waves. But it doesn't take much to tip the balance, plummeting this huge reef into disaster. It might happen sonner than you think. Eighteen million years ago, a series of r

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—14

These destructive waves are as much a part of the reefs life cycle as the animals that inhabit it, and the corals that make it. But out here, there is another miracle. A hundred miles from the coast, In the midst of this huge flat sea, suddenly and w

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—12

All lava has a chemical signature that tells scientists where it came from and when it was erupting. The higher up the old volcano, the more pristine the rocks will be. They are the last remaining evidence of the eruption which created this volcano m

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—11

So we're looking at the core of the volcano which is referred to as Mount Warning. That peak extends up to just a little over 1, 1 00 meters. But when it was active, the peak of this volcano was 6, 000 feet high. Millions of years of wind and weather

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—10

But the wonky holes will never be completely covered up, because coral cant grow in freshwater. Theyll remain an indelible reminder of the reef's past lives. But the origins of the reef lie even further back in time. And to understand them means crac

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—9

Here it is. Got it, I think. A spring. And whats actually coming out of this is fresh water. You can drink. You see this stuff bubbling out? This is what the traditional owners of this place call 'buiur bindi''fresh water in the ocean'. The locals ca

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—8

For thousands of years, this powerful current has regenerated the reef. But it can not repair everything. Beneath the waves lie deeper scarsthe largest coral reef on Earth is home to a dazzling diversity of marine species, some found nowhere else on

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—7

The reef was left high and dry, exposed to air and harsh sun. A trillion tiny creatures died in their own homes. For the coral, it was an apocalypse. When the ice age ended, the sea came back and submerged the dead reef. But what brought it back to l

英语听力：自然百科 澳大利亚大堡礁 Great Barrier Reef—6

Like these sea fans, the last frontier of life on the reef. The divers reach their target-- a massive ridge, 190 feet down. Here, the air they are breathing is under pressure, squeezed down so that there's more gas in every lungful. They have to hope

英语听力：自然百科 野性俄罗斯之西伯利亚 Siberia—13

Away from the rocks and into the grasslands, the family of ground squirrels keep a watchful eye. At just three weeks old, four siblings have started to explore the world beyond their burrow. Like Meerkats in Africa, vigilance is key. They stay alert

英语听力：自然百科 大迁徙 Great Migrations—1

They're born to move, to move or die, forging ahead against terrifying odds, navigating the first of millions of miles, spanning continents on fledgling wings, clattering ever onwards. Right now, our planet is on the march, on the wing, on the run, a