Level 4 Reading 2A

Reading 2A

阅读2A

LIVING LIGHT The ability of some species to create light—known as bioluminescence—is both magical and commonplace. Magical, because of its glimmering beauty. Commonplace, because many life forms can do it. On land the most familiar examples are fireflies, flashing to attract mates on a warm summer night. But there are other luminous land organisms, including glow-worms, millipedes, and some 90 species of fungus. Even some birds, such as the Atlantic puffin, have beaks that glow in the dark. But the real biological light show takes place in the sea. Here, an astonishing number of beings can make light. Some, such as ostracods, are like ocean fireflies, using flashes of light to attract a mate. There are also glowing bacteria, and light-making fish, squid, and jellyfish. Indeed, of all the groups of organisms known to make light, more than four-fifths live in the ocean. As a place to live, the ocean has a couple of peculiarities. Firstly, there is almost nowhere to hide, so being invisible is very important. Secondly, as you descend, sunlight disappears. At first, red light is absorbed. Then the yellow and green parts

活光 一些物种创造光的能力——被称为生物发光——既神奇又普遍。 神奇，因为它闪闪发光的美丽。 很常见，因为许多生命形式都能做到。 在陆地上，最熟悉的例子是萤火虫，在温暖的夏夜闪烁以吸引配偶。 但还有其他发光的陆地生物， 包括萤火虫、千足虫和约90种真菌。 甚至一些鸟类，如大西洋海雀，也有在黑暗中发光的喙。 但真正的生物灯光秀发生在海里。 在这里，数量惊人的生物可以发光。 有些，如介形虫，就像海洋萤火虫，利用闪光来吸引配偶。 还有发光的细菌，以及发光的鱼类、鱿鱼和水母。 事实上，在所有已知的发光生物中，超过五分之四生活在海洋中。 作为一个居住的地方，海洋有几个特点。 首先，几乎无处可藏，所以隐形非常重要。 其次，当你下降时，阳光消失了。 首先，红光被吸收。 然后是黄色和绿色部分

of the spectrum disappear, leaving just the blue. At 200 meters below the surface, the ocean becomes a kind of perpetual twilight, and at 600 meters the blue fades out too. In fact, most of the ocean is as black as the night sky. These factors make light uniquely useful as a weapon or a veil. Hiding with Light In the ocean's upper layers, where light penetrates, creatures need to blend in to survive. Any life form that stands out is in danger of being spotted by predators— especially those swimming below, looking up. Many life forms solve this problem by avoiding the light zone during the day. Others—such as jellyfish and swimming snails—are transparent, ghostlike creatures,almost impossible to see. Other sea species use light to survive in the upper layers—but how? Some, such as certain shrimp and squid, illuminate their bellies to match the light coming from above. This allows them to become invisible to predators below. Their light can be turned on and off at will—some even have a dimmer switch. For example, certain types of shrimp can alter how much light they give off, depending on the brightness of the water around them. If a cloud passes overhead and briefly blocks the light, the shrimp will dim itself accordingly. But if the aim is to remain invisible, why do some creatures light up when they are touched, or when the water nearby is disturbed? A couple of reasons. First, a sudden burst of light may startle a predator, giving the prey a chance to escape. Some kinds of deep-sea squid, for example, give a big squirt of light before darting off into the gloom. Second, there is the principle of "the enemy of my enemy is my friend." Giving off light can help summon the predator of your predator. Known as the "burglar alarm" effect, this is especially useful for tiny life forms, such as dinoflagellates, that cannot swim fast. For such small beings, water is too viscous to allow a quick getaway— it would be like trying to swim through syrup. Instead, when threatened by a shrimp, for example, these organisms light up. The flashes attract larger fish that are better able to spot—and eat—the shrimp. The chief defense for these tiny organisms is therefore not fight or flight—but light. STARS OF THE SEA One of the best places in the world to see a natural light show is Vieques, a small island that belongs to Puerto Rico. The island is famous for its bahia bioluminiscente, or "bio bay"—home to countless dinoflagellates. These dust-size beings are named for their two flagella and the whirling motion they make (dinos means "whirling" in Greek). Dinoflagellates light up whenever the water around them moves; they are the organisms typically responsible for the flashes of light you sometimes see when swimming or boating on a dark night. Visitors to Vieques can join an evening tour group and set out across the bay in transparent canoes. The island has only a few streetlights, so when the moon is not yet risen, the sea is dark—and the sky is full of stars. Fish dart through the water, looking like meteors. Eventually, the movement of the canoes disturbs the dinoflagellates, and they light up in a bright, flickering stream. Watching them through the canoe's transparent floor can give a powerful impression that the water is part of the sky, and you are paddling through the stars.

光谱中的蓝色消失了，只剩下蓝色。 在海面以下200米处，海洋变成了一种永恒的黄昏， 在600米处，蓝色也渐渐消失了。 事实上，大部分海洋都像夜空一样黑。 这些因素使光作为武器或面纱具有独特的用途。 用光隐藏 在光线穿透的海洋上层，生物需要融入其中才能生存。 任何突出的生命形式都有被捕食者发现的危险-- 尤其是那些在下面游泳，抬头看的人。 许多生命形式通过在白天避开光区来解决这个问题。 其他动物，如水母和游动的蜗牛，是透明的、幽灵般的生物，几乎看不见。 其他海洋物种利用光在上层生存，但如何生存呢？ 有些，如某些虾和鱿鱼，会照亮它们的腹部，以匹配来自上方的光线。 这使得它们对下面的捕食者来说变得隐形。 他们的灯可以随意打开和关闭——有些甚至有一个调光开关。 例如，某些类型的虾可以改变它们发出的光线， 这取决于它们周围水的亮度。 如果一朵云从头顶飞过并短暂遮挡了光线， 虾会相应地变暗。 但如果目的是保持隐形， 为什么有些生物在被触碰或附近的水受到干扰时会发光？ 有几个原因。 首先，突然的光线可能会吓到捕食者，给猎物一个逃跑的机会。 例如，某些种类的深海鱿鱼在冲进黑暗之前会发出一大束光。 第二，有“敌人的敌人就是朋友”的原则 发光有助于召唤捕食者的捕食者。 被称为“防盗警报”效应， 这对于不能快速游动的微小生命形式，如甲藻，尤其有用。 对于这样的小生物来说，水太粘稠了，无法快速逃离-- 这就像试图游过糖浆。 相反，例如，当受到虾的威胁时，这些生物会发光。 闪光吸引了更大的鱼，它们能够更好地发现并吃掉虾。 因此，这些微小生物的主要防御不是战斗或逃跑，而是光。 大海之星 世界上观看自然光秀的最佳地点之一是别克斯岛， 属于波多黎各的一个小岛。 该岛以其生物发光区或“生物湾”而闻名，那里是无数甲藻的家园。 这些尘埃大小的生物以它们的两个鞭毛命名 以及它们所做的旋转运动（dinos在希腊语中意为“旋转”）。 甲藻在周围的水移动时就会发光； 它们是典型的罪魁祸首 因为你在黑夜游泳或划船时有时会看到闪光。 别克斯岛的游客可以参加晚间旅游团，乘坐透明独木舟穿过海湾。 岛上只有几盏路灯， 所以当月亮还没有升起时，大海是黑暗的，天空布满了星星。 鱼在水中飞快地游动，看起来像流星。 最终，独木舟的移动扰乱了甲藻， 它们在明亮闪烁的溪流中闪闪发光。 透过独木舟透明的地板看着他们，会给人一种强烈的印象 水是天空的一部分，你在群星间划桨。

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