它们还必须不停地游动以避免下沉，因为大多数鱼基本上或完全失去了鱼鳔，这个充满气体的囊帮助大多数其他鱼保持浮力。
They must also keep swimming to keep from sinking, since most have largely or completely lost the swim bladder, the gas-filled sac that helps most other fish remain buoyant.
囊泡的气体和一条细长的形态存在，应大力改善其在弗里克塞尔湖完全粹水层浮力。
The presence of gas vesicles and a long thin morphology should greatly improve its buoyancy in the completely unmixed water column of Lake Fryxell.
气球：一种大型气密球囊，内充热空气或轻于空气的气体（如氦或氢），以产生浮力，可在大气中上升和飘浮。
Balloon: Large airtight bag filled with hot air or a lighter-than-air gas such as helium or hydrogen that can rise and float in the atmosphere.
比较使用热空气或使用低于空气质量的气体产生浮力的气球，操作方便。
Compared with balloons using hot air or gas of which the mass is lower than that of air to produce the buoyancy, the vacuum balloon is convenient to operate.
比较使用热空气或使用低于空气质量的气体产生浮力的气球，操作方便。
Compared with balloons using hot air or gas of which the mass is lower than that of air to produce the buoyancy, the vacuum balloon is convenient to operate.
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