We have three types of tears – basal, reflex and psychic. Psychic tears, the ones we produce when we are sad, have a different chemical make up than the other two and contain a natural painkiller, leucine enkephalin, which is perhaps why we feel better after we cry.
In the Amazon, butterflies will drink the tears of turtles to provide necessary sodium in their diet.
In Victorian times bottles were used to collect tears with a special stopper that allowed the tears to evaporate. When the tears were gone the mourning period was over.
The same parasympathetic system that commands your colon to go to the bathroom, is also the same system that controls your tears. Sometimes, these signals get crossed which is why some people shed tears when they poop.
Some bees drink human tears.
Tears are made up of almost the exact same ingredients as urine.
In space, no one can hear you cry. Because you can’t. Astronauts are unable to cry properly because there is no gravity and tears cannot flow properly as they would on Earth. It is possible to produce tears in space – but they would leave the eye and float around.