Researchers: No faking it, crocodile tears are real

When someone feigns sadness they “cry crocodile tears,” a phrase that comes from an old myth that the animals cry while eating.

Now, a University of Florida researcher has concluded that crocodiles really do bawl while banqueting – but for physiological reasons rather than rascally reptilian remorse.

UF zoologist Kent Vliet observed and videotaped four captive caimans and three alligators, both close relatives of the crocodile, while eating on a spit of dry land at Florida’s St. Augustine Alligator Farm Zoological Park.

He found that five of the seven animals teared up as they tore into their food, with some of their eyes even frothing and bubbling.

“There are a lot of references in general literature to crocodiles feeding and crying, but it’s almost entirely anecdotal,” Vliet said. “And from the biological perspective there is quite a bit of confusion on the subject in the scientific literature, so we decided to take a closer look.”

A paper about the research appears in the latest edition of the journal BioScience.

Vliet said he began the project after a call from D. Malcolm Shaner, a consultant in neurology at Kaiser Permanente, West Los Angeles, and an associate clinical professor of neurology at the University of California, Los Angeles.

Shaner, who co-authored the paper, was investigating a relatively rare syndrome associated with human facial palsy that causes sufferers to cry while eating. For a presentation he planned to give at a conference of clinical neurologists, he wanted to know if physicians’ general term for the syndrome, crocodile tears, had any basis in biological fact.

Shaner and Vliet uncovered numerous references to crocodile tears in books published from hundreds of years ago to the present.

The term may have gained wide popularity as a result of a passage in one book, “The Voyage and Travel of Sir John Mandeville,” first published in 1400 and read widely, they write.

Says the passage, “In that country be a general plenty of crocodiles …These serpents slay men and they eat them weeping.”

Shaner and Vliet also found reference to crocodiles crying in scientific literature, but it was contradictory or confusing, to say the least.

One scientist, working early last century, decided to try to determine if the myth was true by rubbing onion and salt into crocodiles’ eyes. Shaner said. When they didn’t tear up, he wrongly concluded it was false. As Shaner said, “The problem with those experiments was that he did not examine them when they were eating. He just put onion and salt on their eyes.”

As a result, Vliet decided to do his own observations.

In the myth, crocodiles often cry while eating humans. However, deadpanned Shaner, “we were not able to feed a person to the crocodiles.”

Instead, Vliet had to settle for the dog biscuit-like alligator food that is the staple at the St. Augustine alligator farm. He decided to observe alligators and caimans, rather than crocodiles, because they are trained at the farm to feed on dry land. That’s critical to seeing the tearing because in water the animals’ eyes would be wet anyway.

The farm’s keepers don’t train the crocodiles to feed on land because they are so agile and aggressive, Vliet said. But he said he feels sure they would have the same reaction as alligators and caimans, because all are closely related crocodilians.

What causes the tears remains a bit of a mystery.

Vliet said he believes they may occur as a result of the animals hissing and huffing, a behavior that often accompanies feeding. Air forced through the sinuses may mix with tears in the crocodiles’ lacrimal, or tear, glands emptying into the eye.

But one thing is sure: faux grief is not a factor. “In my experience,” Vliet said, “when crocodiles take something into their mouth, they mean it.”

Source: University of Florida

Related stories:

From the egg, baby crocodiles call to each other and to mom
For the first time, researchers have shown that the pre-hatching calls of baby Nile crocodiles actually mean something to their siblings and to their mothers. The calls—which are perfectly audible to humans and sound like "umph! umph! umph!"—tell the others in the nest that it's time to hatch, according to the report in the June 23rd issue of Current Biology, a Cell Press publication. Those cries also tell the mother croc to start digging up the nest.
Researchers find human virus in chimpanzees
After studying chimpanzees in the wilds of Tanzania's Mahale Mountains National Park for the past year as part of a National Science Foundation (NSF) grant, Virginia Tech researcher Dr. Taranjit Kaur and her team have produced powerful scientific evidence that chimpanzees are becoming sick from viral infectious diseases they have likely contracted from humans.
Alligator blood may put the bite on antibiotic-resistant infections
Despite their reputation for deadly attacks on humans and pets, alligators are wiggling their way toward a new role as potential lifesavers in medicine, biochemists in Louisiana reported today at the 235th national meeting of the American Chemical Society. They described how proteins in gator blood may provide a source of powerful new antibiotics to help fight infections associated with diabetic ulcers, severe burns, and “superbugs” that are resistant to conventional medication.
Reptiles' Muscles Move Lungs for Sneaky Maneuvers in Water
Without a ripple in the water, alligators dive, surface or roll sideways, even though they lack flippers or fins. University of Utah biologists discovered gators maneuver silently by using their diaphragm, pelvic, abdominal and rib muscles to shift their lungs like internal floatation devices: toward the tail when they dive, toward the head when they surface and sideways when they roll.
Scientists Discover 'Giant Fossil Frog from Hell'
A giant frog fossil from Madagascar dubbed Beelzebufo or ‘the frog from Hell' has been identified by scientists from UCL (University College London) and Stony Brook University, New York. The discovery of the 70 million year-old fossil frog, of a kind once thought unique to South America, lends weight to a new theory that Madagascar, India and South America were linked until late in the Age of Dinosaurs.
Gotta have heart! Crocodilians bypass their lungs to improve digestion
As perhaps confirmed by their ubiquity on nature cable channels, crocodiles are among nature’s most fearsome predators. When the opportunity arises, crocodilians will gorge, voluntarily consuming meals weighing 23% of their own body weight. This is analogous to a 130 -pound woman eating, at one sitting, a hamburger weighing 30 pounds. But what to do with all of that food" If they do not digest their meal quickly, crocodilians risk death from within, or if they are young, by predators.
Unusual fish-eating dinosaur had crocodile-like skull
An unusual dinosaur has been shown to have a skull that functioned like a fish-eating crocodile, despite looking like a dinosaur. It also possessed two huge hand claws, perhaps used as grappling hooks to lift fish from the water.
Fossils excavated from Bahamian blue hole may give clues of early life
ong before tourists arrived in the Bahamas, ancient visitors took up residence in this archipelago off Florida’s coast and left remains offering stark evidence that the arrival of humans can permanently change -- and eliminate -- life on what had been isolated islands, says a University of Florida researcher.

News discussion:

General Science news