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来源：雅诚德英语网
But daily vertical movements by zooplankton in the ocean—upward by night to seek food, downward by day to escape predators—can also be considered migration.
但是海洋中浮游动物每天的垂直运动——夜里上浮以寻找食物，白天下潜以躲避捕食者——也可以被视作迁徒。
But daily vertical movements by zooplankton in the ocean—upward by night to seek food, downward by day to escape predators—can also be considered migration.
但是海洋中浮游动物每天的垂直运动——夜里上浮以寻找食物，白天下潜以躲避捕食者——也可以被视作迁徒。