Life in the Clear

    Transparent animals let light pass through their bodies the same way light passes through a window. These animals typically live between the surface of the ocean and a depth of about 3,300 feet—as far as most light can reach. Most of them are extremely delicate and can be damaged by a simple touch. Sonke Johnsen, a scientist in biology, says, “These animals live through their life alone. They never touch anything unless they're eating it, or unless something is eating them.”

    And they are as clear as glass. How does an animal become see-through? It's trickier than you might think.

    The objects around you are visible because they interact with light. Light typically travels in a straight line. But some materials slow and scatter(散射) light, bouncing it away from its original path. Others absorb light, stopping it dead in its tracks. Both scattering and absorption make an object look different from other objects around it, so you can see it easily.

But a transparent object doesn't absorb or scatter light, at least not very much, Light can pass through it without bending or stopping. That means a transparent object doesn't look very different from the surrounding air or water. You don't see it —-you see the things behind it.

    To become transparent, an animal needs to keep its body from absorbing or scattering light. Living materials can stop light because they contain pigments(色素) that absorb specific colors of light. But a transparent animal doesn't have pigments, so its tissues won't absorb light. According to Johnsen, avoiding absorption is actually easy. The real challenge is preventing light from scattering.

Animals are built of many different materials—-skin, fat, and more—-and light moves through each at a different speed. Every time light moves into a material with a new speed, it bends and scatters. Transparent animals use different tricks to fight scattering. Some animals are simply very small or extremely flat. Without much tissue to scatter light, it is easier to be see—through. Others build a large, clear mass of non-living jelly-lie(果冻状的)material and spread themselves over it .

    Larger transparent animals have the biggest challenge, because they have to make all the different tissues in their bodies slow down light exactly as much as water does. They need to look uniform. But how they're doing it is still unknown. One thing is clear for these larger animals, staying transparent is an active process. When they die, they turn a non-transparent milky white.

    How many times a day do you check your WeChat(微信) or QQ? When you wake up? Before bed? A dozen times in between? The technology which was supposed to make our lives simple has taken up too much time. The young people spends more than seven hours a day using technological devices(设备), with an extra hour just text-messaging friends.

    The advantage of technological devices is connection: we are in touch with more people during more hours of the day than at any other time in history. But is it possible that we're lonelier than ever? That's what professor Sherry Turkle observes（观察）in her new book, Alone Together, which clearly describes our changing relationship with technology.

For Turkle, technology isn't offering us the lives we want to live. “We're texting people at a distance,” says Turkle, “We're using lifeless objects(物体) to convince(使确信) ourselves that even when we're alone, we feel together. And then when we're with each other, we put ourselves in situations where we are alone—always on our mobile devices. I call it a storm of confusion(困惑) about what's important in our human connections. That's my biggest worry.”

    Besides, communicating online is not equal to face-to-face communication. Online, you can ignore(忽视) others' feelings. In a text message, you can avoid eye contact(目光接触). A number of studies have found that this generation of young people is less sympathetic(有同情心的)than ever. “That doesn't lead to disaster,” says Turkle, “but the disadvantages still cannot be ignored.”

    It is quite apparent that competition surrounds every aspect of human life whether in the United States or the Amazon Rain Forest. Without it we would not have grown into primates(灵长类动物). Or we would probably still be struggling to sharpen a bronze tool while crawling around on four legs in search of meat. Without competition, Columbus wouldn't have discovered America and Edison would never have invented the light bulb.

    Friendship, like all relationship between two people, involves competition. It isn't competition in a traditional sense because there are no goals to be scored and no prize. Perhaps the ecological definition—the simultaneous (同时的)demand by two or more organisms for limited environmental resources, such as nutrients， living space, or light- better explain it.

    As in nature, high school life is governed by a set of laws, similar to a shortened version of Darwin's theory of evolution, overpopulation, and competition. There is an abundance of high school students and to distinguish them, ranking and categorizing(分类)take place. In high school, friendships learn to co-exist with competition even though at times the relationship is rough. In fact, in some circumstances, competition is too much of a burden for a friendship to bear, causing it to fall apart. College admission is the final high school objective. Four years of hard work is to achieve good grades, and a student's fate is determined not only by these achievements, but by the records of thousands of other seniors trying to achieve a similar recognition.

    Nevertheless, by necessity, competition between students exists in all aspects of high school life. It sets and improves the standards in everything from sports to school work. A healthy, friendly competition can have only benefits, but when it becomes too fierce, jealousy can tear friendships apart. Yet, despite all this, without competition, we would be lost.

    Once an Englishman named Jack Brown went to Russia for a holiday. He stayed there for several months and then came home again. Some of his friends visited him a few days after he got back. "I had a very dangerous trip while I was in Russia," Jack said to them. "I wanted to see a friend of mine in the country and the bad weather made me very late. So I was still traveling through a forest in a sleigh(雪橇) when the sun went down. It was a long way from my friend's house when about twenty wolves began to follow my sleigh. It was very dark in the forest. There was thick snow on the ground. It was cold, and there were no houses for miles and miles. First I heard the wolves. The noise was terrible! The horses heard them, too. They were frightened and began running faster. Then I saw long, gray forms among the trees, and soon the wolves were near us. They were running very fast, and they didn't seem to get tired like the horses."

    "What did you do?" one of Jack's friends asked.

    "When the wolves got very near," Jack answered, "I put up my gun and shot the first wolf. The sleigh was moving about, but I hit the animal and killed it. Then all the other wolves stopped and ate it, so our sleigh got away from them for a few minutes."

    "Then they finished their meal, and I heard them coming again. The moon was shining brightly on the snow now, and after a few minutes I saw them running among the trees once more. They came nearer again, and then I shot another of them, and the others stopped once more to eat it."

    "The same thing happened again and again, and my horses became more and more tired and ran slower and slower until, after about two hours, only one wolf was still alive and following us."

    "Wasn't it too fat to run?" one of his friends asked.

    Need a fall fix? Try one from these great places.

    ⒈Mackinac Island, Michigan

    The only way to reach this famed car-free island is by boat and ferry, and once visitors arrive, they are attracted by the history, scenery and fall colors. "It's a throwback to years past, a little town, and there's a big state park as well," Blackwell says. "You're allowed to have boats all around the island."

    ⒉Tellico Lake, Tennessee

    With nearly 400 miles of shoreline, this waterway flowing out of the Great Smoky Mountains is largely unexploited, well-protected in its natural state. Fall visitors find a range of colors reflecting in the clean waters, says Blackwell, who vacationed in the area with his family as a child. "The thick forest there just allows you to see more greenery and wildlife."

    ⒊Dillon Reservoir, Colorado

    With an hour from Denver, this lake is home to what claims to be the nation's highest sailing club, at an altitude of more than 9,000 feet. Marinas in the towns of Dillon and Frisco make it easy to get out on the water and to see the bright yellows and golds of fall leaves. "People are surprised that there's boating in Colorado, and you can see the mountains just before the snowball," Blackwell says.

    ⒋Lake Monroe, Indiana

    The state's largest lake is surrounded by more than 13,000 acres of protected forest and three recreation areas, making it an ideal place to see fall colors, particularly from oaks and the tulip poplar, the state tree. " It's a gem (宝石) in southern Indiana," says Blackwell, who grew up in the area. "There are lots of different activities: canoeing, kayaking and fishing."

As the pandemic makes clear, cities are possibly humanity's greatest invention, but cities with huge populations also make us easily suffer from the rapid spread of disease. Yet humans aren't the only species that face this problem. Honeybees have lived social lives for tens of millions of years, making them some of the most experienced in the battle against infection. And over time, natural selection has given them quite a few impressive strategies for reducing transmission within bee groups.

However, these strategies are not enough to prevent every threat. Honeybees are battling their own global disease, for which they were totally not prepared. A parasitic mite (寄生螨) originally existed only in the groups of Asian honeybees, but later jumped to infect Western honey bees. Today, it has spread to every region where honeybees are kept except Australia and a handful of remote islands, quickly becoming a global disease of the bees.

If left untreated, a group of bees will typically die from the mites within two years. These infections, plus farm chemicals and poor nutrition, have forced beekeepers to struggle to keep their bees alive. Of the 2.6 million honeybee groups in the US, over half of them have parasitic mite.

And that's only the count of those bees that are tested and reported; the actual numbers are likely much higher. Beekeepers have still managed to slowly increase the number of groups they keep, on average, but at a much higher cost.

Western honeybees did not grow with parasitic mite, and the Western bees lack the behavioral features those Asian honeybees have, like permanently burying the members infested by parasitic mite and, perhaps the most extreme strategy, where the bees are so sensitive to parasitic mite that they completely die as soon as infected, sacrificing themselves to prevent the mite from reproducing.