Crocodiles can produce tears.
The old expression “crying crocodile tears” comes from an ancient myth that the reptile cries to lure his prey and cries with sorrow after devouring it. Crocodiles can indeed shed tears, however they are not tears of sympathy or pain. Some people mistakenly think the expression means false tears because crocodile tears are not real. This has also become a mistaken myth.
The legend of the crocodile tears probably began among the Western world in the 15th century. Sometime during that century Sir John Mandeville’s book “The Voyage and Travel of Sir John Mandeville was published. Mandeville’s book contained the passage “In that country be a general plenty of crocodiles …These serpents slay men and they eat them weeping.”
Crocodile tears syndrome is the common name given to Bogorad’s Syndrome, a facial nerve disorder causing unemotional tearing to occur while the victim is eating. This use of the term is more accurately synonymous with the reason for a crocodile’a tears. The lacrimal glands in crocodiles serves the same purpose as that they do in humans. They lubricate the eyes by producing a proteinaceous substance.
The Lacrimal glands are paired almond-shaped glands that are located behind each eye in both humans and crocodiles. The fluid, or tears that the lacrimal gland produces then flows into canals spilling over into the lacrimal sac. The secreted tears are collected in a part of the upper eyelid known as the fornix conjunctiva. Then the tears pass over the surface of the eye to small holes in the eyelid’s inner corner. Finally the tears drain into the nose via a passage from the lacrimal sac.
Through the centuries following Mandeville’s passage on crocodile tears, a few scientist would try to devise ways to test what became a hypothesis for their scientific experimentation. Of course the main problem was distinguishing tears from water.
The first hint that crocodile tears was a myth came early in the 20th century when a late 15th century scientist actually rubbed salt and onion into a crocodile’s eyes. Aside from perhaps the creation of a new gourmet dish, the scientist got nothing. There were no crocodile tears.
However, Ken Vliet, a zoologist from the University of Florida has actually video-tapped a crocodile crying while eating. He used captive animals trained to feed on dry land.The tapes definitely show the animal’s dry eyes welling up, even frothing while eating.
It is now thought that the crocodile’s tears are the result of all the hissing and huffing the animal displays while eating. Air gets pushed through the sinuses. This then forces tears from the lacrimal glands.