揽瓜阁俱乐部第三期 Day3 2020.07.22
【自然科学-动物】 Dolphins can learn from peers how to use shells as tools （464字 精读 必做篇）
For some bottlenose dolphins, finding a meal may be about who you know.
Dolphins often learn how to hunt from their mothers. But when it comes to at least one foraging trick, Indo-Pacific bottlenose dolphins in Western Australia's Shark Bay pick up the behavior from their peers, researchers argue in a report published online June 25 in Current Biology.
While previous studies have suggested that dolphins learn from peers, this study is the first to quantify the importance of social networks over other factors, says Sonja Wild, a behavioral ecologist at the University of Konstanz in Germany.
Cetaceans — dolphins, whales and porpoises — are known for using clever strategies to round up meals. Humpback whales (Megaptera novaeangliae) off Alaska sometimes use their fins and circular bubble nets to catch fish. At Shark Bay, Indo-Pacific bottlenose dolphins (Tursiops aduncus) use sea sponges to protect their beaks while rooting for food on the seafloor, a strategy the animals learn from their mothers.
These Shark Bay dolphins also use a more unusual tool-based foraging method called shelling. A dolphin will trap underwater prey in a large sea snail shell, poke its beak into the shell's opening, lift the shell above the water's surface and shake the contents into its mouth.
“It is pretty mind-blowing,” says Wild, who studied these dolphins as a graduate student at the University of Leeds in England. This brief behavior appears to be rare: From 2007 to 2018, Wild and colleagues documented 42 shelling events by 19 individual dolphins out of 5,278 dolphin group encounters in the western gulf of Shark Bay.
The researchers analyzed the behavior of 310 dolphins, including 15 shellers, that had been seen at least 11 times. The dolphins' network of social interactions explained shelling's spread better than other factors, including genetic relatedness and the amount of environmental overlap between dolphins. Wild likens the proliferation of this behavior to the spread of a virus. “Just by spending time with each other, [dolphins] are more likely to transmit those behaviors,” she says. The researchers estimate that 57 percent of the dolphins that shell learned the skill via social transmission, rather than on their own.
But the researchers may be premature in dismissing environmental and maternal factors, says Janet Mann, a biologist at Georgetown University in Washington, D.C., who also studies dolphin behavior at Shark Bay. The environment affects where shelling can occur. “Those shells are found in particular habitats, and animals who overlap in those habitats would have access to those shells, but also bump into each other more often,” she says. A dolphin's shelling behavior could also have been influenced during the tens of thousands of hours the animal spent as a youngster watching its mother.
“Dolphins are smart: They watch each other and see what others do,” she says.
Source: Science News
【自然科学-宇宙】 NASA-SpaceX, Next Chapter in U.S. Space Exploration （375字 2分39秒 精听 必做篇）
先做精听再核对原文哦~
The first crewed orbital launch from the United States in nearly nine years took place on May 30, 2020. The SpaceX Crew Dragon spacecraft with two NASA astronauts on board, Robert Behnken and Douglas Hurley, successfully docked on the International Space Station 19 hours after lift-off.
Speaking after the historic launch, President Donald Trump hailed the “groundbreaking partnership between NASA and SpaceX.” This public-private partnership he said, has “given our nation a gift of an unmatched power: a state-of-the-art spaceship to put our astronauts into orbit at a fraction of the cost of the Space Shuttle.”
This launch marks an exciting turning point for American space exploration. NASA, said President Trump, “will now . . . embark on the most difficult, most daring most audacious missions of humankind:”
“Through NASA’s Artemis program, the United States is preparing for a crewed mission to Mars . . . .The Orion capsules being worked on in this building as part of the Artemis Moon-to-Mars program, those capsules will soon return Americans to lunar orbit for the first time in over 50 years.By 2024, our astronauts will return to the lunar surface to establish a permanent presence and the launching pad to Mars.”
Space travel is not a feat of engineering alone, stressed President Trump. “It’s also a moral endeavor -- a measure of a nation’s vision, its willpower, its place in the world:”
“Exploration is a test of our values and of our faith. America is a nation defined by its commitment to discovery -- to solve mysteries, to chart the unknown, to press the limits, to achieve the fullest expression of life’s potential, and to ensure that America is the nation that always leads the way, especially in space.”
The United States is venturing out to explore the new, magnificent frontier called space, declared President Trump. “As our brave American astronauts shake the Earth and blaze a trail of fire and steel into the heavens, we proclaim for all to hear that we have not yet tested the full strength of the American character, and the world has not yet seen the full glory of the American spirit. For our country, for our children, and for humanity’s march into the stars, the best is yet to come.”
Source: VOA
【笔记格式要求】
精读笔记格式要求： 1.总结文章中心大意 2.总结分论点或每段段落大意 3.摘抄印象深刻或者觉得优美的句子 4.总结文章中的生词 5.记录阅读时间、总结时间、总时间
精听笔记格式要求： 1.逐句听写整篇文章 2.对照原文修改听写稿，标记出错原因 3.总结文章中心大意 4.总结精听过程中的生词 5.记录听写时间、总结时间、总时间
这里也给大家两点学习小建议哦~ 精读：如遇到读不懂的复杂句，建议找出句子主干，分析句子成分，也可以尝试翻译句子来帮助理解~ 精听：建议每句不要反复纠结听，如果听 5 遍都没听出来，那就跳过，等完成后再回听总结原因，时间宝贵，不要过于执着哦~
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发表于 2020-7-21 22:22:40
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