But these defenses can get overwhelmed if the oxygen concentration is too high.

但是如果氧浓度过高，这些防御系统就会不堪重负。

This allows jellyfish to thrive in waters that have extremely low oxygen concentrations.

这使得水母能够在极低氧浓度的水域中茁壮成长。

You can then adjust this oxygen concentration between 30 to 100 before being delivered to the baby.

然后你可以将氧气浓度调节在 30 到 100 之间，然后再把它送到宝宝身边。

It is why people with lower oxygen concentration sometimes remove protective clothes atop Mount Everest; some freeze to death.

这就是为什么缺氧的人有时会在珠穆朗玛峰顶上脱下防护服；其中一些人甚至会因此冻死。

Through their nerve nets, they can sense the temperature, salinity of the water, oxygen concentration, gravity, ocean currents and more.

通过它们的神经网络，它们可以感知水温、盐度、氧气浓度、重力、洋流等等。

The oxygen concentration rose and fell until eventually it reached the approximate 21% we have today.

氧气浓度上升和下降，直到最终达到我们今天的大约 21%。

But for organisms that live in the water, it's even worse, because oxygen concentrations are always lower in water than they are in the air.

但对于生活在水中的生物来说，情况更糟， 因为水中的氧气浓度总是低于空气中的氧气浓度。