the first one just like this
Creatures of the Thermal Vents
by Dawn Stover
The three-person submersible Alvin sank through the cold, dark waters of the Pacific Ocean for more than an hour, finally touching down on the sea floor more than 8,000 feet below the surface. It was December 1993, and the scientists inside the sub had come to this stretch of the East Pacific Rise, an underwater mountain range about 500 miles southwest of Acapulco, Mexico, to inspect a recently formed hydrothermal vent - a fissure in the ocean bottom that leaks scalding, acidic water.
Peering out through the subs tiny windows, the visitors were astonished to see thickets of giant tube worms, some four feet tall. The tail ends of the worms were firmly planted on the ocean floor, while red plumes on the other ends swayed like a field of poppies. Alvin had brought researchers to the same spot less than two years earlier, when they had seen none of these strange creatures. Measurements at the site have since shown that individual tube worms can increase in length at a rate of more than 33 inches per year, making them the fastest-growing marine invertebrates. That means tube worms can colonize a vent more rapidly than scientists once thought.
photo ? Al Giddings/Images Unlimited, Inc.
The giant tube worm is one of the most conspicuous members of a diverse community that forms around hydrothermal vents. Scientists once thought that no living thing could survive the harsh combination of toxic chemicals, high temperatures, high pressures, and total darkness at these vents. But in 1977, researchers diving in Alvin discovered tube worms and other bizarre organisms thriving at a vent off the Galapagos Islands. Similar communities have since been found at several hundred hot spots around the world. These creatures are like nothing else on Earth.
Vents form where the planets crustal plates are slowly spreading apart and magma is welling up from below to form mountain ranges known as mid-ocean ridges. As cracks form at these spreading centers, seawater seeps a mile or two down into the hot rock. Enriched with minerals leached from the rock, the water heats and rises to the ocean floor to form a vent.
Vents are usually clustered in fields, underwater versions of Yellowstones geyser basins. Individual vent openings typically range from less than a half inch to more than six feet in diameter. Such fields are normally found at a depth of more than a mile. Most have been discovered along the crest of the Mid-Oceanic Ridge, a 46,000- mile-long chain of mountains that wraps around Earth like the seams on a baseball. A few vents have also been found at seamounts, underwater volcanoes that are not located at the intersection of crustal plates.
The largest vent field, called TAG , is about the size and shape of a football stadium. Other fields have more whimsical names like Clam Acres, Mussel Bed, Rose Garden, Garden of Eden, Broken Spur, and Lucky Strike. Snow Blower is named for the white, flaky bacteria discharged from its vents. Genesis is a vent that sputtered out but came back to life a few years later
安南辞任叙利亚特使 联合国大会通过决议谴责叙利亚暴力
享受这世间的种种苦乐悲喜
重新审视ETF基金
CEO不值那么多钱
红丝带
英男子因看奥运面无表情 被警方逮捕
惠普对旗下Autonomy减记88亿美元
东亚岛屿争端的来龙去脉
Lex专栏:奢侈品企业失去光环
名言警句中英文对照--悲伤篇
杰尼亚走向“坎坷之路”
引进“银联” 伦敦丽思营收创记录
你真漂亮,她说 Beautiful, She Said
自信
Tommy’s Essay 汤米的随笔
希腊有望获得440亿欧元纾困贷款
微笑与爱心
唤醒灵魂的力量-音乐
生命即是奇迹 Miraculous
什么才是真正的“江南Style”?
Lex专栏:铜价反弹
如再活一次,一切将会不同
只有发现自己才会享受人生
Permission to Fail 允许失败
伦敦奥运影响英国国债拍卖
以色列称保加利亚巴士爆炸与伊朗有关
美总统林肯葛底斯堡演说
为人父母
冯建梅事件和解 政府补偿7万余元
英语美文 犹太女孩谱写别样《神曲》
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |