Out there is a river valley that’s been carved into the rock. It’s been carved by running water, just flew down here smoothly off this rock bed and then cascaded down to the valley north there. Six thousand years ago, that was a big river.
Satellite images reveal that the river bed I’m standing in is just one of a network of past river valleys that crisscrossed the Sahara desert. Ten thousand years ago, this dry, empty place was entirely different. Little is known about the early Saharans who lived here then, but we do know that they depended entirely on water. Water formed the lakes in which they swam. Water nourished the plants which fed the animals they hunted. Water filled the clay pots from which they drank, but then the climate changed.
About five and a half thousand years ago, the Sahara began to dry. The rains failed, the river shrank and the lakes dried out. For the early Saharan people, there was only one option – to follow the rains and abandon the desert.
The fortunes of the early Saharan people revealed a universal timeless truth: our fate is inextricably linked to water. The problem is the water never stands still. It’s always on the move across the planet. We think of this as a blue planet, but while water is abundant, most of it is no use. More than ninety-seven percent of the earth’s water is salty ocean which we can’t drink or use to grow crops. Less than three percent is fresh water on which all human life hangs. What’s more, that tiny fraction is often hard to depend on, because fresh water has a life cycle all of its own.
The water seems so familiar, doesn’t it? But to see its remarkable qualities, you have to go to some extreme length.
The fresh water that we depend on begins its life in the oceans. As the sun’s rays beat down on the surface of the sea, they heat the water molecules until some evaporate. It’s the start of an extraordinary journey.
Here as water evaporates, it feels like it vanishes into thin air there. Although we barely notice it, water molecules are suspended around us all the time, just that we are only aware of it when they clump together as clouds.
a journey one time, less than a thousandth of the world’s water is up here in the atmosphere. It may not seem much, but this is what spreads water from the seas to the land.
The water molecule doesn’t hang around up here for very long. It fact, it spends less time up there in the atmosphere than the any other time of its journey, a mere nine days until a typical water molecule crashes the earth as rain.
For most of us, rain is perhaps the most familiar stage of the water cycle, but notoriously the least reliable.
As the water falls as rain, it joins a big system, cascading and carving its way across the land surface as streams and rivers. Look at that, water, absolutely everywhere.
Rivers and rain are of the parts of the water cycle that we depend on and yet they are only a tiny proportion of the world’s fresh water, amazingly two percent of all fresh water on the planet, the rest of the earth fresh water is locked away, down there on the ground.
What a landing.
The vast majority of it is stored as ice. Most of the rest seeps deep into the earth where it’s known as groundwater. Hidden away down here is the planet’s second large store of fresh water, but in the end, all water arrives back in the oceans and the cycle begins again.
Of all our planet’s forces, perhaps none has greater power over us than water. For me, water is the most magical force on earth. The presence of water shapes, renews and nourishes our planet.
Oh, my God ! You get all wet there!
It’s our planet’s lifeblood. It pumps through it continuously, delivering vital ingredients for life.
Water makes us alive. Yet, water is just one of the ways that the power of the planet has shaped our lives. The earth has immense power and yet that’s rarely mentioned in our history books. I’m here to change that. I’m exploring four great planetary forces that have influenced our history.
The power of the deep earth; the few technological innovation-wind, that has shaped the fate of entire continents; and fire, which gave us the power to conquer the planet.
But I’m going to start with water, the magic of water is that it’s constantly transforming itself, shifting between guises and from place to place, our struggle to control it has been behind the rise and fall of some of the greatest civilizations on earth.
The center of the Sahara Desert in North Africa, one of the driest places on earth.
I’m over six hours drive from civilization. Temperatures here regularly reach 100 degrees Fahrenheit, but there’s less than half an inch of rainfall each year.
Ah,the whole things are moving. It’s like walking on water.
Yet, hidden amongst these dry dunes are clues that point to the dramatic influence the planet has had on human lives.
I’ve come here because although you’ll never know it, the story of this place is all about water. The clues are etched into that rock face there. Prehistoric rock outdating about 6,000 years in the pattern of the almost unlikely characteristics you’ve ever seen.
Whoa, what is that? Is it a giraffe? It’s a giraffe. Look at that, here is a neck, here is its ear. Look at that, it’s an eye, isn’t it? That’s really natural, isn’t it? And that looks like a giraffe, dipping its head/ and drinking some water. We’ve got a herd of giraffes here.
Looks like two cats. They are fighting. That, what is that? Looks like a figure of, a figure of a man who’s wearing a burqa. And that’s clearly a crocodile which is especially odd here, that’s an aquatic animal. It doesn’t just paddle around. It needs a lot of water to live in. I find all the creatures that are depicted on these rocks are not desert animals. They need wet conditions.
In such a parched wilderness, how can this be? The only explanation is that 6,000 years ago, this place was wet. Once you know what to look for, the evidence is all around.
The Dead Sea is the lowest point on earth and runs more than 50 miles in length and stretches 11 miles across its wildest point, bordering Israel, The West Bank and Jordan. Large sections of the coast are fenced off and sign posted in Hebrew and English: Warning of sinkholes.
The sea’s dropping water levels is leading to dangerous consequences. In April, an Israeli hiker wandered into an area that had no warning signs and was critically injured when he fell into a sinkhole.
“Due to the rapid drop, the ground water are now facing with the salt rock and the salt rock is undergoing a very rapid dissolution. Cavities（空腔） are formed inside and eventually the surface collapses down to these cavities and these are therefore the sinkholes.”
Geologist Eli Raz himself became the victim of a sinkhole several years ago.
“(I) just remembered that I was busy by documenting a new sinkhole, and then suddenly I found myself covered by a pile of avalanche on the bottom of a sinkhole.”
He spent 14 hours at the bottom before his rescue, and even wrote his will, not knowing he would be saved.
“I just can tell you that it was terrible, very frightened and in the first place, in the beginning, I started to write my will without knowing that somebody will find it of course.”
Now Raz is working to save others from the similar fate, leading an effort to map the sinkholes that are spreading on the banks of the saltwater lake.
The formation of the Dead Sea sinkholes are caused by a drop in the sea’s water level due to limited rainfall, the diversion of much needed water from its upstream sources, pollution, and industrial evaporation of water by the Dead Sea mineral industry. As the sea levels drop, high levels of salt are left behind in the soil. When fresh water washes in and dissolves the salts, cavities are created, causing sinkholes.
Detecting potential sinkholes is crucial because they not only damage the environment, but pose a direct threat to the tourist industry and agriculture.
These underground pits can now be better detected by a new monitoring system. The Geophysical Institute（地球物理研究所） of Israel, along with the Geological Survey of Israel, has been trying to locate sinkholes when they are being created and to follow them. The monitoring can help reveal dangerous sinkhole zones in their early stages.
“We developed a methodology of combining geophysical prediction of sinkholes appearing at the Dead Sea costal plane. What we have (as) a problem now is we need to create at least (a) few geophysical teams with the aim of the constant geophysical monitoring of the dangerous area.”
When a sinkhole is deemed dangerous, reportedly, crews can fill it in with cement or initiate its collapse before it would happen naturally.
In the 80 years that records have been kept, the water level in the Dead Sea has dropped by over 65 feet. The sea has shrunk by more than a third. And in the absence of any expensive water replenishment（补充，补给） plan, the sea is expected to shrink to about two thirds of its current size over roughly the next century.
Day breaks in Sanaa, Yemen as the call to prayer rouses the inhabitants of this ancient city as it has for hundreds of years. This capital city, nestled at an elevation of over 7,000 feet in the Yemeni highland, is one of the oldest continually inhabited cities in the world.
In the Medieval areas, towering mud-brick houses with white plaster highlights are oddly reminiscent of the spectacular gingerbread city. While in the Labyrinth souks, Yemenis haggle for spice, jewelry and other goods just as they have for centuries.
A walk through these narrow passageways quickly reveals one striking piece of merchandise, an accessory the Yemeni gentleman can’t be without–the Jambiya. These ornate burly knives are worn prominently, tucked into thick embroidered belts. And while they may seem fearsome to western sensibilities, the Jambiya is almost never used as a weapon, instead it serves as a sign of Yemeni manhood.
In the cramped quarters of the souk, blacksmiths intendedly work metal into the unmistakable hook-shaped blades. Rows of gleaming daggers are proudly displayed in market stalls. Their prices range from a few dollars to a staggering one million dollars for a Jambiya with impeccable craftsmanship and illustrious history, but the prestige of these items can come at a high price other than money.
The worth of these daggers is often defined by the handle, traditionally made from rhinoceros horn, price for the unique patina it exhibits. Jambiyas have often been cited as a major underlying cause for rhino poaching. Despite bans by the Yemeni government and international community on the trade of horns, they continue to be used by some knife makers. Conservationists and government officials have tried to stamp out the use by encouraging alternative materials, like water buffalo horn or camel hoofs, but in this country where change creeps slowly and tradition remains strong, a rhino horn Jambiya may be a steady symbol for some time to come.
Why is this diver burrowing into the bottom of this mini lake.She is literally disappearing into the sand and gravel of the water’s floor.Only debris and the occasional bubbles from her breathing tank are visible. She is part of a project, largely funded by National Geographic, to dive into the sacred pools of the ancient Maya.
“Our exploration team discovered this upwelling, it’s an underwater spring upwelling, and it provides this magical experience because it’s located at the bottom of a very large crater, and you can come down, down, down, down into this large crater, and in the bottom is this boiling mass of sediment that’s actually being rolled and boiled, it’s almost like a natural lava lamp, went in over the lip of the crater, descended down into the bottom, and I didn’t want to have any interference with the water that was already in the pool, and so it required a little bit of digging,and frankly it was extremely low visibility down there but below the actual base of sediment, there’s about one and a half meters more space. The water coming out of the bottom of this spring,coming into the pool,is chemically quite distinct from the water in the pool.”
But this is just the beginning. The dives also revealed clues to past life here, and the first for the country of Belize. Scientists discovered several fossil beds around 60-90 feet below the surface, including femur bones the size of a bowling ball. They also found tusks and \ bones. These are the first recorded fossils ever found in Belize.
“And we left those in place. We have only removed a few small fossils so we can actually determine, are they fossilized, or bone, and they are definitely fossilized, so we know they have to be of a certain age. but were they here , were these megafuta present during occupation by humans about 20,000 years ago , 15,000 years ago, or are they much older?”
The dives were made in several pools in central Belize earlier this year in an area known as Cara Blanca, The researchers found evidence that the eight pools of the 25 they studied are likely connected through underground passages.Principal Investigator Lisa Lucero says the major goal is to look for archaeological remains underwater.
“Because the Maya considered openings in the earth caves, water bodies , as porters to the underworld of \. And because the thousands of caves that have been found have offerings, ancient Maya offerings , we just knew there be offerings at the bottom of the pool, so we came with the goal of trying to dive to look for these offerings.”
Though they didn’t find offerings on the first dives, they did find surrounding sherds in a pool near remains of Maya buildings, constructed around 1,100 to 1,300 years ago.Lucero says there is no indication this area had many residences, but rather was likely a pilgrimage site, with Maya traveling here from hundreds of miles away,because at least one of the pools was found to be around 200 feet deep, and littered with trees and silt, more sophisticated diving equipment is needed for future dives. And Lucero believes there are more significant Maya offerings at these depths.
The research is being conducted under the auspices of the Belize Institute of Archaeology, and the scientists plan to return for more exploration.
Ever since man first began setting out for new lands by small boats heading over unknown horizons, he’s been searching for among other things, paradise. And paradise in the Tuamotus, a small archipelago in the Pacific about 200 miles northeast of Tahiti, means coconuts, digging clams, spear fishing and camping on the beach with the surf lulling to sleep.
But paradise today is not without its concerns. The biggest worry here is global warming. The 78 atolls that make up the two Tuamotus are just thin coral reefs, at their highest they are 10 feet above sea level.
As the average temperature of the oceans climb, estimates are that many of these living, breathing, still growing reefs and the lagoons they protect will very likely disappear in the next 50 to 100 years as the seas rise.
Frank Murphy is a University of California of Berkeley-trained marine biologist.
“It struck me the other day when my children arrived at Tahiti and saw that for the first time, that actually in their life time, this could disappear, and it’s pretty amazing.”
Fishing is a primary source of both food and cash. Doriat will take a dozen big My-Mys from his plywood boat which will sail on the island of Fakarava. Gathering and drying the white meat of coconut known as copra is the chain’s biggest business. A 100-pound sack sells for 38 dollars. A hard working family will produce 100 sacks a month.
In the past 20 years, a new economy has boomed in Tuamotus – black pearls. Pamala and Valda are 22 and have their own pearl growing business on a tiny spit of sand in the middle of a lagoon at Tuwao. They have thousands of oysters drowned just below the surface. Valda takes daily care of the boxes of the oysters, making sure they are close tightly to protect them from their natural predators. Pamala works 8 hours a day, seeding as many as 400 oysters a day. Once planted below the surface, each oyster will nurture a pearl for a year and a half.
Outsiders come looking for paradise and leave with many questions.
Is it ideal here?
Is it paradise?
As close as you can come, a tropical dream comes true.
Yet it is clear these tiny spits of land at the midst of a giant sea of blue paradise are at some risk. These westerners are happy to have seen a glimpse of paradise since it may soon change forever.
New Words and Phrases
the line or circle that forms the apparent boundary between earth and sky.
a large group or chain of islands,a large group or chain of islands
the principal island of the Society Islands, in the S Pacific
to fish underwater using a spearlike implement used manually or propelled mechanically
to put to sleep or rest by soothing means,to give or lead to feel a false sense of safety; cause to be less alert, aware, or watchful.
The United States has started the largest infrastructure project in human history, a complete top-to-bottom overhaul of our entire electrical supply grid, which is getting new intelligent devices at every step from the power company’s generators to the devices in our homes and making sure every component is secure from attack, while also elegant control of water, gas and sewage systems. And this total make-over must happen while the whole system is operating online at peak capacity, while it’s growing in fact. In short, we’ve begun building a smarter power grid, one that works pretty much like the internet. You could call it, the InterGrid.
Our aging power grid system is starting to fail. We’ve seen more blackouts and brownouts, and it runs inefficiently, wasting carbon into the air. New clean sources like wind and solar which make power only part of the time need intelligent pathways to get the consumers, and the Americans prefer the power they use to have been produced by Americans. Right now, our fragile, less-than-smart power grid, interconnect nearly 10,000 utility plants, that’s well over a million mega watts of generating capacity. About half it comes from burning coal. At least one third of the United States carbon output, maybe more, comes from power generation. Almost one fifth of our power steams onto the grid from the boiling water, heated by the nation’s 104 nuclear reactors. Nearly six percent of the electricity used in the US comes from flowing or falling water, hydroelectric power generated at river dams.
But the same six percent of all the electric power that’s produced gets lost before it gets where it’s supposed to go. It either melts away as heat as it travels long more than a quarter million miles of metallic wire, or it simply shorts to grid, undetected somewhere within the constant maintenance headache of the decaying patchwork of cable towers and poles.
Reclaiming just that six percent would be the equivalent of taking 55 million cars off the world in terms of the petroleum saved and green house gases prevented. For the past quarter century, the peak demand for power has been outpacing investment in new transmission line and power regulation systems that can only react when something goes wrong. They are not good at spotting problems before they happen. The old grid flies perilously close to the breaking point, every hot day in sunlight cities.
According the Department of Energy, US businesses use over a hundred billion dollars a year to blackouts and brownouts. The power that does arrive has to be used as soon as it gets there. But up till now, there hasn’t been a good way for consumers to tell the power company how much power they might want to purchase. To keep our electric grid from grinding to a halt, the new InterGrid will work on a principle known as prices to devices.
If you knew the electric rates were going to spike very high this afternoon, you might decide to leave your home air conditioner off while you are out of the house. Well, suppose your air conditioner, in fact your entire home, knew it before you. What if those device, your thermostats, washers, driers, refrigerators, Jacuzzis could make decisions about how much energy to purchase according to your preset preference and tell the utility company what you are willing to pay. And that’s truly speaking truth to power.
To see exactly how the InterGrid will listen to your demands and how it will keep us healthy and secure, please play Part Two of the electric InterGrid.
In Part I of the Electric InterGrid , we saw how consumers and utility companies could both save money and liberate much less carbon into the Atmosphere, if our power network became intelligent and self-aware.
But for this idea to work, every team that makes electricity and most things that use it, must interact with one another. Like the Internet, devices on the InterGrid must be plugged in play, so that any device can hear or speak to any other. And like the Internet, the InterGrid will grow a little with each clever new gadget.
Now, the downside of the power grid that works just like a web, is that it takes close to hacker attacks, launched by pranksters, but also from organized and well-funded terrorists. Soon, every smart meter in every home and business will be something akin to computer virus protection.
The InterGrid must also defend against assaults from Planet Earth itself. Let’s say one day, maybe 10 years from now, a monster hurricane comes ashore, knocking off power. The intelligent InterGrid instantly begins matching energy sources to critical needs, places like hospitals and fire stations must be back online first.
But this InterGrid isn’t depending only on utility power from power plants far away. After all, lines may be down over a large area. It’s also intelligently hunting a whole local energy sources. The solar panels are on your neighbor’s roof, lock logging a hybrid car in your drive lane. Refuels in your daughter’s school – every little bit helps.
Smartly switching power to vital local services like a phone system or a police station is called Ilingding. And it can keep whole communities afloat in times of trouble.
To keep powers flowing, operators must know what the grid is doing, at every level from local streets to international transition lines, to keep small failures from cascading out of control. This is a prototype for a systme to do just that. It’s called VERDY – Visual Energy resources Dynamically on Earth. It overlays different kinds of realtime information on googleearth, bringing weather data, showing which specific power lines are out, and who owns what wires, and how much of the population is affected. It can even pull up web cans of trafic, and evacuation routes.
Believing where everything is completely normal, utility managers still want to know as much as they possibly can, because, frankly, they prefer to produce only as much power as customers are willing to pay for.
Electricity moves essentially at the speed of light. If it is not used, as soon as it’s generated, it goes to waste. But the alternative of black-out is obviously quite inevitable. So, the current grid, depends on what the utility companies call “Peaker Plants.” Nobody likes them. Peakers cost money to build and maintain. They run on fuel that isn’t bought at the best market prices. So “Peak Power” becomes expensive power. Yet “Peaker Plants” sit idle most of the time.
This new intelligent InterGrid could eliminate most “Peakers” by anticipating consumers’ demands through interactive price signals. As engineers say, “If you can measure it, you can manage it.” But ultimately the InterGrid will be judged on how well it does 4 things:
Keeping money in consumer’s pockets;
Making communities safer, more secure and icreasingly self-reliant;
Supporting stable power utilities running on sustainable domestic resources;
Protecting and improving earth environment.
So, what will it cost to do all this? Estimate for the total investment needed here in the United States at about 1.5 trillion dollars over 20 years beginning 2010. What amazingly, that’s just about the amount of money needed anyway, just to keep the lights on, whether we make the grid smarter, cleaner and safer, or just simply keep it working alone.
Nature’s latest report from the world of paleontology challenges the assumptions made by everyone until now about when animals first walked the earth.
This is footprint of early tetrapods. We have here, for example, digits, impressions, and something like their pads. This is important.
I’ve been working personally in this field since the mid 1990s. I’ve had over 20 publications in ‘Nature’, and this is the most important paper that I have ever worked on.
Footprints in a Polish quarry tell the tetrapods which walked the earth 20 million years before we thought any animal had left the sea.
This is your little friend, isn’t it? Oh my word. Oh, wonderful. Look at that!
Until only a few months ago, this was an accurate model of a kind of animal paleontologists believed existed in the Middle Devonian Period, with fins but no proper feet. The new model is quite different.
Legs stick out and thighs can flex forwards. Then, it had to be an animal like this, a primitive land vertebrate, not a fish.
And if you are not sure you believe it, the Nature paper and the full film offer the proof.
New Words and Phrases
paleontology n. 古生物学
footprint n. 脚印，足迹
Polish adj. 波兰的，波兰人的，波兰语的 n. 波兰语
quarry n. 采石场，猎获物，出处，被追逐的目标 v. 挖出，苦心找出
Middle Devonian Period 中泥盆纪
It’s Friday afternoon at a village bakery in Hara Kebira,this tiny Jewish community is preparing for the sabbat meal bringing pots of soup to be heated in the wood oven.Today’s customers are Jewish,but the baker here is Muslim.In much of the world,that’s a novelty.Here it’s daily life.
“We work together.We do business together.We help each other.One time it’s a Jew.One time it’s a Muslim.It’s easy here in Djerba and it’s been going on for a long time.And this didn’t start yesterday,for us that’s everyday.”
Tunisia is 98% Muslim and Jews here are small minority out of about 3000 in the entire country roughly have lived on Djerba Island and nearly all in the village of Hara Kebira.It might be a recipe for discrimination but instead it’s a model for coexistence.Djerban say they get along because they always have.Living together is a part of their heritage.
“We see each other all the time because we live together.This isn’t 10 years or even 20.We’ve been living together for hundreds of years.We’re used to it.”
Djerba’s Jewish community maybe the oldest Jewish settlement in the world.Tradition holds at the first Jews came here more than 2,500 years ago and founded the grip of synagogue.In more recent times,immigrants came to Djerba from Spain and Italy pleaing prosecution.It hasn’t always for Jews here either.And Djerba’s Jewish population has dimished in the last 50 years.But a small community has endured.In the village Muslim and Jewish shots sit side by side.
Hara Kebira has several synagogues,a mosque and a Jewish cemetery.A broad neighbourhood life brings them together.Religious life still keeps them separate.Those communities are very traditional.An integration can only go so far.
“You never find a Jew here marries to a Muslim,not hatred,it’s just our tradition.Jews with Jews.For our religion that will always stay the same.”
Living together can be a tough balance to strike.And with turmoil in the Middle-East,some worry that things may be changing.Still there is hope.This Djerba classroom has a sign on the door that reads “Love thy neighbour”.Inside the students are learning about religion.In their community,they’re learning about getting along.In Djerba,despite the tensions in the outside world,”Love Thy Neighbour” is still a goal,shared by Jews and Muslims alike.
New Words and Phrases
bakery n. 面包店
Muslim n. 穆斯林，穆罕默德信徒
novelty n. 新奇，新奇的事物，小装饰
roughly adv. 概略地，粗糙地，粗鲁地
recipe n. 食谱，秘诀，药方
discrimination n. 歧视，辨别力，识别
coexistence n. 共存，和平共处
heritage n. 遗产，继承物，传统
As the water is warm and tides grow high, horseshoe crabs leave the ocean floor and make their way to the shores and estuaries of the Atlantic Coast. Here in the sheltered waters of South Carolina, they suddenly emerge by the thousands in the spawning ritual they’ve performed for hundreds of millions of years. On the highest tides, they drag themselves to shore to lay their eggs. Crabs don’t mature till they are nine or ten. By then, they’ve molted for the last time and their permanent shells can host an ecosystem of hitchhikers. Horseshoe crabs are safest on the ocean floor, but the only way to carry on the species is to take a risk.
We see the ones that see us come and turn and take off to the water. We caught him before he knows us. You know.
Jerry Golt and his father Bob have worked these waters for decades.
We work the moons. The horseshoe crabs come up and spawn on the moons in the springtime.
If you actually get into the water, you can feel them swimming and sometimes you can’t even catch them because they’ll get to swimming so fast. A lot of people seem to be scared when they first see them on the beaches. They do look a little scary but what I do is put them right up against my face and as you can see they do not hurt. Their pinchers are all very light. These are harmless. I just like them.
Mine is bigger. Mine is younger. Huh…
For 15 years, South Carolina has been collecting horseshoe crabs for fishing bait. Now, only fishermen with special licenses are allowed to gather crabs for biomedical use and only if they return the crabs alive. Few of us realized just how valuable the horseshoe crab is.
When I first started 37 years ago, we were allowed to harvest them. There was no recording; there was nothing. And they became fair game and I was involved with selling them for bait. And then a doctor came down and he said that if I didn’t sell bait crabs anymore, he would be interested in the laboratory.
Normal fishing is, as you know, you catch it, you ice it, and you deliver it to the table, and you eat it. The horseshoe crabs we actually catch them, take them to the lab, and they bleed them and we bring them back and release them. So we are borrowing the crabs, this is what we are doing.
Crabs that are borrowed end up a couple of hours away at the Endosafe Laboratories in Charleston. Here in this alien world, they are given a rigorous cleaning to prep them for the process ahead. For the past 30 years, the biomedical industry has been mining the medical equivalent of gold. Endosafe is one of the only four labs in the world that produces a derivative of horseshoe crab blood. Their blood has a clotting agent that’s used to detect minute levels of bacteria. But what’s truly surprising is the color. The crab’s blue blood is an evolutionary gift that’s helped them survive the eons.
Male or female? A small male would be good. OK!
Doctor Norman Wainwright has been working with horseshoe crabs for most of his career, studying the remarkable properties of their blood.
The beautiful blue color is a result of its blood containing copper as an oxygen carrying pigment instead of hemoglobin which contains iron. I am adding a suspension of E. coli bacteria.
At the first sign of bacteria, the crab’s blood forms a protective clot.
Look at that, this is perfect. This is the horseshoe crab cells protecting the animal from infection. Any type of leakage of seawater into their blood system will trigger this response, seal the wound and they actually are proteins in the clot itself that kill the bacteria. They are almost the primitive antibiotics.
The phenomenon caught the attention of the biomedical community in the 70s, they’ve been putting it to work for us ever since. Up to a third of the crab’s blood is removed during the process, yet most of them survive. One quart of horseshoe crab blood is worth about 15,000 dollars. It’s a multi-million-dollar industry. The clotting agent called Lysate is used to test intravenous drugs for bacteria. No IV drug reaches the market without being tested on horseshoe crab blood. It’s an FDA regulation.
Years ago, the only way to screen for toxins dangerous to humans was to use live rabbits. Feverish bunnies revealed contamination and the test was slow. Horseshoe crab blood takes an hour tops and most of the crabs survive the process. Scientists are exploring alternatives that would make bleeding crabs unnecessary. But each day we are finding more ways the horseshoe crab can help us with everything from sutures to contact lenses.
New Words and Phrases
horseshoe crabs 鲎，马蹄蟹
ocean floor 海底
estuaries n. 河口，江口，海湾
sheltered waters 隐蔽水域
spawn n. 卵，产物，后代，结果 vt. 产卵，种菌丝于，产生，造成 vi. 产卵，大量生产
ritual n. 仪式，典礼，宗教仪式，固定程序 adj. 仪式的，老规矩的，惯常的
lay eggs 下蛋，产卵
molt n. 换毛，脱皮，换毛期 v. 换毛，脱毛
ecosystem n. 生态系统
hitchhiker n. 搭便车的旅行者，短篇广告，顺便插入的广告
carry on the species 繁衍生息
take a risk 冒险
take off v. 起飞，脱掉，取消，匆匆离开，成功，去除，起跳，拿走
waters n. 水域，领海，水体
springtime n. 春季，青春期，初期