In May 2007 the first unequivocal proof that crocodiles shed tears while eating was published in Bioscience magazine although for many years the false remorse of hungry crocodiles has been legendary. Part of the reason it has taken so long to get scientific proof of such a well observed phenomenon is that crocodiles are very difficult to study close-up while they are eating without yourself becoming part of the meal.

In December 2013, a boat full of tourists led by Carlos de la Rosa, an aquatic ecologist and director of the La Selva Biological Station in San Pedro, Costa Rica photographed a Julia butterfly and a bee drinking the tears from a spectacled caiman. You can see the footage on Youtube:

This fortunate encounter is not the first time observers have noticed tear feeding behaviour in insects, Bees drinking the tears of a yellow-spotted river turtle in Yasuní National Park, in the Ecuadorian Amazon has been documented in 2012.The insects are thought to be seeking salt which is only found in very low quantities in nectar and important for egg production. The observations raise questions about the relationship between crocodiles and insects. Is this an example of mutualism? Is tear feeding an essential part of the insect's nutrition? How important is this interaction to the ecosystem?

“The scientific community has drifted very strongly toward high-tech types of studies,” said de la Rosa, “And natural history itself, which is simple observations of events and phenomena in nature, has declined." This interaction is unlikely to be reproducible in the lab and we may never have noticed it without a little serendipity during field research or, in this case, on an eco-tourist river cruise.

Serendipity is referred to several times in the IB Biology guide to illustrate the nature of science. In the discovery of cyclins, Alexander Fleming's famous discovery of penecillin, William Beaumont's observation of gastric acid in digestion.

On the subject of tears there has also been some amazing research on human tear-eating bees but that is another story.