托福听力常考知识点剖析：海星
- 2018年05月08日11:47 来源：小站整理
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托福听力涉及话题多样，尤其是偏向于学术课堂场景的讲座类，经常考到一些我们并不熟悉的学科，适当的掌握一些背景知识和常考考点有助于我们更迅速精准地听懂听力内容。海星是托福听力常考的知识点之一，无论是机经真题还是托福官方真题Official都能见到它的身影，下面我们就结合官方真题Official31的Lecture3,了解一下托福听力中会如何考察海星吧。
Introduction：
Starfish
海星主要分布于世界各地的浅海底沙地或礁石上,主要以浮游生物为食物。我们对它并不陌生。然而,我们对它的生态却了解甚少。海星看上去不像是动物,而且从其外观和缓慢的动作来看, 很难想象出,海星竟是一种贪婪的食肉动物,它对海洋生态系统和生物进化还起着非同凡响的重要作用。这也就是它为何在世界上广泛分布的原因。
Background information：
Starfish are keystone species in theirrespective marine communities. Their relatively large sizes, diverse diets andability to adapt to different environments makes them ecologically important.
Starfish sometimes have negative effects onecosystems. Outbreaks of crown-of-thorns starfish have caused damage to coralreefs in Northeast Australia and French Polynesia. A study in Polynesia foundthat coral cover declined drastically with the arrival of migratory starfish in2006, dropping from 50% to under 5% in three years. This had an unintendedeffect on reef-feeding fish and the whole benthic community. Asterias amurensisis one of a few echinoderm invasive species. Its larvae likely arrived in Tasmaniafrom central Japan via water discharged from ships in the 1980s. The specieshas since grown in numbers to the point where they threaten commerciallyimportantbivalve populations. As such, they are considered pests, and are onthe Invasive Species Specialist Group's list of the world's 100 worst invasivespecies.
Knowledge points：
1. 海星在它们各自生活的生态圈有着重要的地位。它们相对大的尺寸,不同的饮食习惯以及能适应不同环境的能力使它们有重要的生态价值。
2. 生态圈里,海星有时候也会有负面作用。刺冠海星的爆发已经造成了东北澳大利亚和法属波利尼西亚的珊瑚的破坏。
3. 在波利尼西亚的一项研究发现,当 2006 年海星迁移来之后,珊瑚覆盖率急剧下降, 三年间从 50%下降到 5%。这对以珊瑚为食的鱼类和底栖生物群落产生了影响。
Vocabulary prediction：
Spawn 产卵
Fluctuation 波动
Runoff 径流
Phytoplankton 浮游植物
Test Point – 官方真题Official31L3
Professor
We've been talking about the decline ofcoral reefs in tropical areas all over the world...urn... how natural andman-made stresses are causing them to degrade, and in some cases, to die. Sonow let's focus on a specific example of a natural predator that can cause alot of damage to coral reefs—the Crown of Thorns, or CoT starfish. The Cotstarfish is found on coral reefs in the tropical Pacific Ocean and it eatscoral. Now, in small numbers, the starfish don't affect coral reefsdramatically. But periodically, starfish population explodes. And when thathappens, the reefs can become badly damaged or even destroyed, something we aretrying very hard to prevent. For example, during the 1960s, there was anoutbreak of CoT starfish in the Great Barrier Reef, off the east coast ofAustralia. Luckily, the CoT starfish population gradually declined on its ownand the reefs recovered.
But we were left wondering - what cause thepopulation to increase so suddenly? Well, over the years, we've come up with afew hypotheses. All still hotly debated.
Knowledge points
1.CoT starfish 存在于热带太平洋的珊瑚礁上,并且发现它是吃珊瑚的。
2.当大量的海星蔓延时,暗礁被严重损坏。比如 20 世界 70 年代,在澳大利亚东海岸,大堡礁有大规模的海星的爆发。幸运的是,海星数量逐渐下降,珊瑚礁逐渐恢复。
