for National Geographic News
For centuries insincere humans have been said to cry crocodile tears—a nod to the famous tale that crocs weep with false remorse while devouring their prey.
Now research has shown that some reptiles really do shed tears during a meal, but most likely for biological rather than emotional reasons.
"Generally crocodile tears are pretty similar to human tears," said study co-author Kent Vliet of the University of Florida.
"You see moisture in their eyes or collecting in the corners of the eyes. At times it will drip out of the corner and run down their face just like you'd expect a tear to run down a child's face."
Of course, there is no "eater's remorse" involved when a croc turns on the water works.
"Crocodiles appear to produce tears all the time," said croc expert Adam Britton, founder of the informational Web site Crocodilian.com.
"Their function is—like our own tears—to lubricate the eye. This may be even more relevant for crocodiles because they have a third eyelid," also known as a nictitating membrane.
Britton was unaffiliated with Vliet's research, which was published in the latest edition of the journal BioScience.
Crocodile tears have been difficult to observe because the animals spend so much time in the water and are too aggressive to be trained to eat on land.
(Related news: "Croc Attack Sheds Light on 'Disastrous' Conditions at Taiwan Zoo" [May 18, 2007].)
The University of Florida's Vliet revealed the behavior with controlled feedings of captive alligators and caimans—two animals closely related to crocs—that had become conditioned to eating on dry land.
SOURCES AND RELATED WEB SITES