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Crocodile tears please thirsty butterflies and bees

May 1, 2014
Life & Non-humans

The butterfly (Dryas iulia) and the bee (Centris sp.) were most likely seeking scarce minerals and an extra boost of protein. On a beautiful December day in 2013, they found the precious nutrients in the tears of a spectacled caiman (Caiman crocodilus), relaxing on the banks of the Río Puerto Viejo in northeastern Costa Rica.

A boat carrying students, photographers, and aquatic ecologist Carlos de la Rosa was passing slowing and quietly by, and caught the moment on film. They watched [and photographed] in barely suppressed excitement for a quarter of an hour while the caiman basked placidly and the insects fluttered about the corners of its eyes.

De la Rosa reported the encounter in a peer-reviewed letter in the May 2014 issue of the Ecological Society of America’s journal Frontiers in Ecology and the Environment.

“It was one of those natural history moments that you long to see up close,” said de la Rosa, the director of the La Selva Biological Station for the Organization for Tropical Field Studies in San Pedro, Costa Rica. “But then the question becomes, what’s going on in here? Why are these insects tapping into this resource?”

Though bountiful in the ocean, salt is often a rare and valuable resource on land, especially for vegetarians. It is not uncommon to see butterflies sipping mineral-laden water from mud puddles. When minerals are rare in the soil, animals sometimes gather salt and other rare minerals and proteins from sweat, tears, urine, and even blood.

De la Rosa had seen butterflies and moths in the Amazon feeding on the tears of turtles and a few caimans. Tear-drinking “lachryphagous” behavior in bees had only recently been observed by biologists. He remembered a 2012 report of a solitary bee sipping the tears of a yellow-spotted river turtle in Ecuador’s Yasuní National Park. But how common is this behavior?

Back at the field station, he did a little research. He was surprised to find more evidence of tear-drinking than he expected in the collective online record of wilderness enthusiasts, casual tourists, professional photographers, and scientists. He now thinks the phenomenon may not be as rare as biologists had assumed—just hard to witness.

“I did a Google search for images and I found out that it is quite common! A lot of people have recorded butterflies, and some bees, doing this,” said de la Rosa.

A search of the scientific literature produced a detailed study of bees drinking human tears in Thailand, as well as the remembered October 2012 “Trails and Tribulations” story about the Ecuadorian bee and the river turtle byOlivier Dangles and Jérôme Casas in ESA’s Frontiers. This experience reminds us that the world still has many surprises for ecologists, de la Rosa said. There so much still to be studied. De la Rosa is a specialist in the biology of non-biting midges, and a natural historian, with his eyes always open to new discoveries. Scientists at La Selva have discovered hundreds of species of aquatic insects that are still unnamed and undescribed.

“I have over 450 undescribed species from Costa Rica in my laboratory. If I did nothing for the rest of my life but collaborate with taxonomists and try to describe those, I would never get done,” he said.

De la Rosa’s job as director of La Selva Biological Station brings him an unusual number of serendipitous encounters with wildlife. He lives on site in the lowland rainforest, and he never needs an alarm clock. Howler monkeys wake him every morning.

“I learned I have to carry a camera with me 24/7, because you never know what you’re going to find when you’re walking to the office or the dining hall,” he said. One day, he spied a new species of dragonfly on his way to breakfast. It had emerged from its larval form in the small pool of water caught in the cupped leaves of a bromeliad plant. He did a double-take. Dragonflies don’t live on bromeliads. Or do they?

“Those are the kinds of things that, you know, you don’t plan for them, you can’t plan for them,” de la Rosa said. There was only one known species of dragonfly in the world that lives in bromeliads. Now there will be two. “You just keep your eyes open and have curiosity, and when you see something that doesn’t seem to fit, dig.”


Crocodile tears please thirsty butterflies and bees

24 Responses to Crocodile tears please thirsty butterflies and bees

  1. u14084351 May 7, 2014 at 2:27 pm #

    Everyone has heard the phrase “crying crocodile tears” which is used to describe a false display of emotion. Crocodile tears are real and like our own tears it comes from the lachrymal glands. The fluid helps the crocodile to clean the eye and probably also helps to reduce bacterial growth and prevents the eye from drying out.
    It is amazing to read about these insects that have the guts to go and drink the caiman’s tears to satisfy their mineral need, I would not dare to attempt something like that. It is scary to think about how much we miss out on small things like this. There is so many things we still need to learn, but we need to see to truly understand. Nature is beautiful, bizarre and brutal.

  2. u14051606 May 5, 2014 at 2:08 am #

    This article is enlightening. It is something out of the ordinary. People don’t usually talk about crocodile tears in a literal sense. It’s interesting to see how organisms help each other. There is so much in the world that has not yet been discovered and it would be amazing to witness a few of these discoveries..

  3. 14006716 May 4, 2014 at 11:36 am #

    Quite enlightening, often one does not realize just how much there is that scientists still have to discover or how seemingly rare phenomena might in fact be quite common. Perhaps such phenomena seem rare as they are not often witnessed (“hard to witness” as stated in the article), or are such phenomena becoming more common due to changing conditions perhaps still it is simply a case of a lack of understanding and if one learned more about the phenomena they would be far easier to witness (as one would know why they occur and so when and where to look for them).

    It is exciting as a science student to be reminded that there are still plenty of discoveries to make and new understandings to form. It would certainty seem advantageous to keep an inquisitive mind, one need never stop learning.

  4. Karen Bezuidenhout May 4, 2014 at 8:15 am #

    This is an incredible article. It makes you realize how much you’re missing when you’re looking but not really seeing. And to think that there are so many species which have not been named. Who knows what’s still out there.

    As I read this article, I wondered how these butterflies and bees know when they need these minerals. Do they, for example, get dizzy when deficient in a certain mineral, like humans often do when they do not have enough iron in their blood. Do they maybe get “cravings” after it?

    These suggestions might sound a little bizarre and “creative”, But as Einstein said: “Imagination is more important than knowledge. For knowledge is limited to all we now know and understand, while imagination embraces the entire world, and all there ever will be to know and understand.”

  5. Damon Munday (14008948) May 3, 2014 at 11:41 pm #

    What an incredible and beautiful world we live in! Some things in nature just seem to blow my mind. This world is constantly changing with new industrial developments which exploit and disturb natural habitats by polluting the soil and air. We can’t be sure for how much longer scientists will still be able to study such phenomena in the natural world. Resources such as minerals and nutrients are becoming harder and harder to find and therefore, like the butterfly and the caiman, animals may resort to extreme symbiotic relationships to survive.
    You would think that we know so much about the natural world and what lies out there, but this just shows how much of our vast world we are yet to discover. We can find beauty in the smallest of things, and all it takes is a special moment empowered by curiosity.

  6. N Prinsloo (14010454) May 3, 2014 at 8:26 pm #

    Wow, how interesting was this. I would never in a million years have guessed that a butterfly and a bee would go and drink the tears of a crocodile or turtle for minerals. This have made my eyes open to see that what we think we know of nature, there is always something new that can be discovered. Take for instance the 450 undescribed species form Costa Rica, I surely think there must be much more that we does not even know about. Nature have so much more to offer us, and we does not even know that. Nothing can exists alone, everything lives in harmony with each other. The whole ecosystem are interacting with one another. I would have never though that a bee or butterfly would need the tears of a crocodile or turtle for survival, but now it seems that they actually need one another. If one species becomes extinct, the whole ecosystem suffers under it. I think we don’t know in what extend the ecosystem are link together.

  7. CM (14104335) May 3, 2014 at 2:05 pm #

    It is amazing to see how everything in nature is connected in some way. Seeing how a dangerous animal like a caiman lives in harmony with fragile insects like butterflies and bees is truly magnificent. It just shows how amazing nature was created. The symbiotic relationship between the specific insects and the caiman is very interesting. Determining the exact type of relationship, whether it’s parasitic, mutualistic or commensialistic, could probably be done by determining the function or cause of the tears. According to an article the function of the tears of a crocodile is mainly to lubricate the eye. Therefor I believe that this occurrence is a display of commensialism. The mentioned insects benefit by receiving nutrients, while the caiman stays unaffected.

    What I also found very interesting and astonishing is the fact that there are still so many species that are undescribed. That just makes you wonder how many species are still undiscovered. Finding and classifying new species must be a very intricate process. You should have a very good idea of already existing species to be able to classify a new one. The fact that we still know so little about nature and make new discoveries every day, is humbling and it makes you appreciate nature so much more.

  8. u13236955 May 3, 2014 at 7:44 am #

    It is quite amazing how organisms interact with each other in the ecosystem. A crocodile known for its notorious predating methods-It’s amazing to see it calm throughout the entire process. Who would have thought that one of the most dangerous creatures known thus far actually is not entirely a threat to other species? As for the bees drinking human tears, I thought the main attractant for bees is nectar. I’m so eager to read some of the findings about this research

  9. u13236955 May 3, 2014 at 7:20 am #

    It is quite amazing how animals and plants interact in the ecosystem.There are still some undiscovered stories about how animals interact with each other.It is so fascinating to think that a crocodile known for its notorious predating methods remains calm throughout the process.The new information has caught my interest,who would have thought that butterflies can get minerals from a crocodile tear.As for the bees drinking human tears-I Thought the main attrant for bees is nectar,I’m so eager to read some of the findings of this research.

  10. 14077583 May 3, 2014 at 3:34 am #

    I love the symbiotic relationship explained here – that harmless butterflies and dangerous crocodiles can live together in harmony and help each other.
    The article also shows that a little curiosity did not hurt anyone, rather (in this article) it helped discover a bizarre phenomenon as well as a new species of dragonfly that lives on the leaves of a bromeliad plant.
    This was actually a very interesting read. It shows that nature is a beautiful mystery to us.

  11. 14051992(OS Moche) May 3, 2014 at 2:38 am #

    It is nice to know that crocodile tears are useful and appreciated unlike their figurative meaning. It is quite fascinating how extreme symbiosis is at times. I understand the excitement of the students and photographers because I am sure most people would agree that nature tells the best stories and sharing in them.

  12. Dylan Mackenzie (14049580) May 3, 2014 at 12:04 am #

    With what May have been a subjective topic, with possible metaphorical meanings, it was definitely the more direct and interesting point of view chosen. This piece, what many would say is another battle of David and Goliath, or a clash of big versus small so to speak. However this clash is not one of violence, but rather one of complex balance and natural understanding between two contrasting species who most would not expect to be dependent on each other. This article is an astounding example of the intricacies of nature and it emphasizes that independence is not part of natures vocabulary. Nature is a big cycle of reliance and therefore this is a brilliant article that expresses the fundamentals of nature. I would never have expected that what is seen as waste to one species could be utilized by another species whose survival rate in modern times is very sensitive due to rapidly changing environments. This article also portrays a sense of trust and unity as the crocodiles let a potentially dangerous insect near what could be perceived as the crocodiles only soft or vulnerable spot so to speak. I found this blog extremely interesting as it opened my eyes to the unexpected.

  13. Advaitaa Haripershad 14227496 May 2, 2014 at 9:09 am #

    The title definitely captured my attention as I was curious to know about the benefits of crocodile tears and insects. My initial thoughts where that this was a metaphorical topic based on ‘human crocodile tears’ as 14033021 mentioned. This mutualistic relationship is a bizarre phenomenon which is indicative about the coherent cycle of nature. It is astounding to know that the dissolved nutrients in crocodile tears are beneficial to the smaller insects. Also 14015278 makes a valid hypothese that the crocodiles benefit from the insects removing excess water along with wastes which could lead to infections. This is article has immensely enlightened me as I was unaware of this rare occurrence. It also serves as an explanation as to why bees have been noted to fly towards people’s eyes.

  14. u14007259 May 2, 2014 at 7:38 am #

    It is hard to believe that a tear ,especially that of a crocodile can help butterflies and bees to quench their thirst. Although it has been known that butterflies feed on the tears of turtles and a few caimans it has only recently been found that bees too, can feed on the tears of other animals which is interesting.It is amazing how two seemingly different creatures can live in an environment where one of them is benefited by the other in a tremendous way. This article shows just how completely different creatures such as a reptile and an insect can benefit each other in such a simple way.

  15. Amir 14033021 May 2, 2014 at 4:37 am #

    This article immediately caught my attention as i always wanted to know what it meant when people say:”to shed crocodile tears.” this text did not answer that question however it was very interesting none the less. I always saw crocodiles as being dangerous and violent creatures, however now I see that they also contribute to the well being of other creatures in nature as well. I believe that the reason for butterflies actually drinking crocodile tears is that it is a lot easier to absorb dissolved nutrients in the form of the tears rather then trying to obtain them from the sand.

  16. Justine 14077142 May 2, 2014 at 2:32 am #

    I’ll admit, at first I didn’t think this article would be very interesting, but as I read I found it enlightening to see just how nothing in nature ever goes to waste and that the saying ‘Where there’s a will, there’s a way’ reigns true in a sense, as the Dryas iulia and the Centris sp. sought after proteins and necessary minerals in the most unlikely places that many humans (including myself) wouldn’t go anywhere near. The mutualistic relationship offered by the Caiman crocodilus is actually quite incredible.

    I feel like there is a need to expand research into the concept of insects extracting minerals from animal tears, to enhance it’s capabilities and in turn enhance the lives of the insect populations.

    As stated in the article, minerals are a scarce commodity on land, so one wonders how the insects will make do as the already scare resources become scarcer. As well as it is possible for us humans ourselves could assist these creatures. Should some species die out, it will create a ripple effect and lead to an imbalance in the food web. Should the butterflies die out, there will be less pollination and less blooming flowers etc etc, hence a butterfly effect (pun intended).

    Okay, it may sound slightly far-fetched but anything is possible.

    (Corrected all the typos in my previous comment)

  17. Justine - 14077142 May 2, 2014 at 1:54 am #

    I’ll admit, at first I didn’t think this article would be very interesting, but as I read I found it enlightening to see just how nothing in nature ever goes to waste and that the saying ‘Where there’s a will, there’s a way’ reigns true in a sense, as the Dryas iulia and the Centris sp sought after proteins and necessary minerals in the most unlikely places that many humans (including myself) wouldn’t go anywhere near. The mutualistic relationship offered by the Caiman crocodilus is actually quite incredible.

    I feel like there is a need to expand research into these concepts of insects taking minerals from animal tear to enhance it’s capabilities and in turn enhance the lives of the insect populations.

    As stated in the article, minerals are a scarce commodities on land, so one wonders how the insects will make do as the already scare resources become scarcer. As well as it is possible for us humans ourselves could assist these creatures. Should some species die out, even the smallest of creatures, will create a ripple effect leads to an imbalance in the food web. Should the butterflies die out, there will be less pollination and less blooming flowers etc etc, hence a butterfly effect (pun intended)

    Okay, it may sound slightly far-fetched but, anything is possible.

  18. 14348315 May 2, 2014 at 1:06 am #

    Nature is something that is so special and also unpredectable. Everyday scientists come across so many new findings and also crave to dig more deeper to understand the the new creature’s life and its ecology and actually how it was formed. New forms and findings always emerges everyday, so a true scientist is always ready to tackle a new scenario every time.

    You might even think that this relationship that is taking place can be a parasitic or a mutualistic relationship according to how a specific person can understands it.Sometimes the things that are revealing themselves as nature provide them to us, are continuosly taking place everyday but sooner or later theories are uprooted, and it is often said to be evolution and there will always be creaction of new species because of so many factors.

  19. 14100322 May 2, 2014 at 12:14 am #

    It is so exciting to find an article as obscure as butterflies drinking the tears of crocodiles and realizing that you actually understand parts of what is going on in the article. It is interesting to note that the interaction between the crocodile and the butterfly is symbiotic in nature as many have suggested.

    I tried to conduct a google search after reading this post to find out why exactly insects need to consume salt but aside from a few Wikipedia posts there weren’t many articles with definite answers. I was under the impression that salt was not good for insects because I had this idea that a slug + salt = death, however I just realized, after another google search, that slugs are molluscs and not insects.

    We are constantly learning new things every day. We are also constantly, like De la Rosa, discovering new things every day. If you are educated enough to realize that it is extremely rare to witness dragonflies on bromeliads then, like De la Rosa, you may stop and take a closer look, but the majority of us wouldn’t even know what a bromeliad looks like which begs the question: how many of us have seen a completely new species and haven’t been any the wiser?

  20. u14010918 May 1, 2014 at 10:05 pm #

    This was an incredible and interesting read for me. To think that small insects like the butterflies and bees would go to any extremes to find a source or salt and protein is incredible and what makes it even more fascinating is, they do this by feeding on the tears of caiman and turtles.

    I do agree with 14015278 that the butterflies’ feeding off of the caiman’s tears is a mutualistic relationship. The butterflies benefit from the salts and other minerals in the crocodile tears whilst the crocodile benefits in the sense that they can prevent infection but one important factor is they use their tears to make a protective layer around their eye. This also helps keep their eye from having infection and other pathogens from entering their eyes.

    It is amazing how many species of animals help one other to survive whether one benefits or not. De La Rosa mentioned that he has 450 undescribed species in his laboratory. This just shows that there are so many species that still has to be discovered and I believe we haven’t seen half of what nature has to offer.

  21. 14096057 May 1, 2014 at 12:37 pm #

    It would be interesting to determine whether the symbiotic relationship between insect and crocodile is mutualistic, commensalistic or even parasitic.

    I agree with 14303273. It really is wonderful how these two animals can live in harmony especially considering that crocodiles have been portrayed as such vicious animals. The phrase “Crying crocodile tears” emphasises this idea as it is derived from the belief that crocodiles shed tears to lure their prey. This article proves the idea wrong as crocodiles are portrayed as gentle creatures allowing insects to feed off them.

    The butterflies’ ability to adapt to finding an alternative source of salt is remarkably evolutionary!

  22. 14303273 May 1, 2014 at 8:45 am #

    Its interesting that animals so far apart on the food chain can live in harmony with each other, effectively helping each other out. This lets you wonder what is still unknown in the amazing world of animals

  23. 14015278 May 1, 2014 at 7:00 am #

    It is always incredible to hear – read – of such happenings. Although they are inexplicable as stated in the article, they are quite phenomenal and are subject to various hypotheses and suggestions. I have heard of similar stories before where a Lion would ‘adopt’ an impala. But this seems, to me, as a sort of mutualistic relationship between the insect and the reptile. The insect benefits from the nutrients in the crocodile’s tears, whilst the crocodile benefits by getting rid of the tears that may prove to cause infections due to stagnation or flies laying eggs in them. I know my ‘benefit’ found for the crocodile may seem far fetched and absurd, it could prove correct as when one regards dogs or cats for instance, their tears are usually a sign of a blockage in the tear duct and lead to a cornea infection. Thus this could likely be some thing of the sort in reptiles. Overall very interesting article and research must continue.

  24. Martine May 1, 2014 at 6:38 am #

    It is amazing how new species keep on evolving. It is also interesting to note how depended we are as species on other species even when it comes from bees drinking human tears as a form of protein. If ever there was a question around symbiotic relationships and evolution, this surely must be the answer.

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