南极的企鹅渴了是直接吃一口雪吗？ 还有类似的没有河流湖泊淡水的地方动物是直接啃雪吗? 第1页

它们可以直接喝海水，而这种行为对于这个星球上大多数鸟类和陆生哺乳动物来说都是致命的。我们人类是不管怎么样都不能直接喝海水的。实际上如果我们强行去喝海水，喝得越多，活活渴死的速度就越快。原因如下：一般情况下我们的尿液比摄入的水的含盐量要高，借此排出体内各种多余的盐分；但是，我们的肾脏不足以让尿液中盐分的浓度与海水中的持平，所以为了能够将你通过喝海水摄入的盐分排出体外，身体需要产生的尿液量将会远远超过你喝下的海水量。你喝的海水越多，身体中盐与水的比例就会越发失调，你也就离致命的脱水状态越近了。

好的，我们现在已经解释清楚了为什么人类不能喝海水，但到底是什么让企鹅这么特殊呢？原因就在于它们有一个叫作眶上腺的腺体，我也想要一个呢。（倒不是说我会多频繁地用到它，毕竟我也不常在海里游泳，但你可以想象一下这么说听上去是不是很棒：“嘿，你想看看我的眶上腺吗？”）有一些企鹅不会刻意去喝海水，只不过它们的食物是海里的鱼类，在把鱼类吞到肚子里的时候难免会灌一肚子的海水。眶上腺就位于企鹅眼睛的上方，它的功能就像肾脏，却能完成7对肾脏的工作量。企鹅的血液循环会经过这里，那些多余的盐分就会在这里被过滤出来。显然这个方法非常有效，你可以看到从企鹅喙上的小鼻孔里流出的那些液体。那可不是鼻涕，而是它们从身体中排出的过量盐分的溶液，这种液体的盐分浓度比企鹅的其他体液高了整整5倍

英文版

The supraorbital gland is a type of lateral nasal gland found in some species of marine birds, particularly penguins, which removes sodium chloride from the bloodstream. The gland's function is similar to that of the kidneys, though it is much more efficient at removing salt, allowing penguins to survive without access to fresh water. Contrary to popular belief, the gland does not directly convert saltwater to freshwater. The term supraorbital refers to the area just above the eye socket (which is known as the orbit).

Living in saltwater environments would naturally pose a large problem for penguins because the ingestion of saltwater would be detrimental to a penguin's health. Although penguins do not directly drink water, it is taken in when they engulf prey. As a result, saltwater enters their system and must be effectively excreted. The supraorbital gland has thus enabled the penguins' survival in such environments due to its water-filtering capability. The gland is located just above the eyes and surrounds a capillary bed in the head. This capillary bed constantly strains out the salt in the saltwater that a penguin takes in. Since the byproduct of the gland has roughly five times as much salt as would normally be found in the animal's fluids, the supraorbital gland is highly efficient.

The penguin excretes the salt byproduct as a brine through its bill. Often, the fluid drips out, and this gives the appearance of a runny nose. However, the fluid may also be sneezed out. In the absence of saltwater, caused by captivity, the supraorbital gland will lie dormant as it has no other purpose. Having a dormant supraorbital gland does not negatively affect the health of a penguin.

参考自Wikipedia以及《万万没想到》