Answer: Cats

Domestic cats are efficient at all sorts of things: tolerating high temperatures, hunting and digesting small prey, and, of course, endearing themselves to humanity to secure lifelong shelter and care. One particular skill that goes unnoticed (and certainly untested among house cats) is their incredibly efficient kidneys.

Not only can cats meet all their water needs simply from the water they extract from the bodies of the small animals they eat but, if necessary, they can rehydrate themselves by drinking salty sea water. While we’d hazard to guess that no cat prefers drinking sea water over a nice fresh bowl of clean spring water, the fact that they can do so without any harm is quite remarkable (as drinking sea water proves fatal for most mammals like humans, dogs, and so on).

Their extremely efficient excretory system is also exactly why cat urine has such a potent smell. In comparison to the urine of dogs (another domestic animal that might make a mess of your rug or mark the side of your sofa), the urine of cats is very concentrated and contains a much higher ratio of excreted waste chemicals to water than most other animals.