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When it comes to a beverage menu, I don't usually want to see "tears" on the list. But these three animals do, including bees whose favorite drink is human tears!

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To bee or not to bee?

That is the question… And researchers finally answered it, when they let bees land in their  eyes in the name of science. It was all to prove that  these bees drink human tears.

And they’re not the only animals  that turn to tear-sipping to get by. So let’s talk about the  different reasons that creatures resort to such a sad, salty choice of snack. [♪ INTRO] The scientific term for one animal drinking another’s tears is lachryphagy,  and there are a lot of reasons why this sad-sounding diet makes a lot of sense. One type of tear-drinker is the erebid moth, and they suck down bird tears for nutrition.

These moths use their proboscis to  feed on bird tears, which are long, tubular structures that insects  use for slurping up food. The moths have a proboscis  that’s long enough to allow it to land on the bird’s neck  to drink those tasty tears, which avoids disturbing the bird and increases the moth’s odds of successfully grabbing a drink. They mainly drink bird tears at  night, when the bird is asleep and immobile, presumably so their  teary-eyed targets doesn't freak out.

You could say that the nutrients  in bird tears attract moths like… well, like moths to a flame. But the thing is, this is a pretty new  thing that researchers have figured out these moths do, so there’s a lot that we just don’t know about why  they do this in the first place. That said, the researchers who  first spotted this behavior have a few hypotheses about what  exactly it is they’re after.

See, the soil in this part  of the world is sodium rich, but only sometimes. Sodium  levels are dependent on flooding, which can be inconsistent. So these moths may be targeting  bird tears specifically when sodium levels in the environment are low and they can’t get it from other sources.

But they may not be after the sodium at all. Instead, the moths might be practicing lachryphagy for the proteins in the tears, like albumin. Getting more nutrients like sodium and proteins increases male-moth reproductive  success, flight performance, and overall fitness, so lachryphagy  is very helpful for the moths.

We also don’t know for sure  how this tear-drinking affects the birds whose eyeballs are getting targeted. Since a proboscis to the eye  doesn’t sound all that sanitary, it’s possible that being targeted by these moths could result in stuff like eye infections. So researchers are definitely  keeping an eye out for moths doing this to learn more.

And  probably, so are the birds. Moths aren’t the only insect  that rely on tear-drinking for super-important nutrition —  cockroaches slurp up tears, too. In a competitive ecosystem with fast-paced nutrient cycling like a rainforest,  it can be hard to keep up in the hunt for nutrient-rich resources.

In this type of environment,  lots of animals practice puddling to get the resources they need. Puddling just refers to drinking  anything from the moist ground, carcasses, and even from other animals’ waste. Which can include tears.

In this case, these cockroaches are all about tear-drinking to get their  daily dose of nutrients. But unlike the moths, cockroaches  don’t have a proboscis, so when they crawl up onto  their target to sap their tears, they have to get much closer to the eye to feed. Which is pretty dangerous,  when you’re a tiny little bug.

Luckily for the cockroaches, their typical daytime targets like crocodiles and turtles are not super interested in eating tiny invertebrates. However, the cockroaches’ nighttime tear-drinking targets are mainly birds  and anoles, which are cute little lizards that are very  interested in eating cockroaches. The cockroaches might be going for these smaller animals at night for safety reasons, presumably because the birds  and anoles would be asleep and less likely to notice the cockroach getting all up in their personal space.

With all this danger, you might be wondering why the cockroaches would even  bother drinking tears at all. It mainly comes down to the cockroach reproductive cycle using up a ton of nitrogen. They need up to 27 times more nitrogen  during the reproductive cycle, and puddling and tear-drinking  are effective ways for cockroaches to get that critical nitrogen,  along with phosphorus and sodium.

Male cockroaches even bring  nitrogen to females in the form of uric acid, to increase the speed of  the female’s reproductive cycles. That means that males who get more nitrogen for their ladies have a better  shot at having more babies, so they’ve got a lot riding on  getting as much nitrogen as they can. Such high stakes means they’re willing  to do some pretty risky things, like climbing into their predator’s  eyeballs to suck their tears.

Anything in the name of love, I guess. This video is supported by Arizona State University’s College of Global Futures. ASU and the College of Global  Futures is the academic home for students who want to create a  more equitable, sustainable, and promise-filled future for everyone.

Their programs help people make a positive impact on the world with their careers. For example, you could  prepare yourself for a future helping us all get what we eat  in a more environmentally s ustainable way with a Bachelor of Science or a Master of Science degree  in Sustainable Food Systems. The undergraduate degree  covers many aspects of food and agriculture through social  and environmental lenses so that by the time you graduate, you’ll feel more empowered to make real change.

If you are looking to advance  your career in food systems, you could consider the master’s program. Through that program, you’ll learn about modern day health, agriculture,  and environmental policies. Then, you’ll get the chance to  come up with your own strategies to lead policy discussions with  food and agriculture policy leaders!

And the best part is that these  degrees are made accessible to way more people because they’re all online! You can go to ASU’s website  and check them out today. But first, back to the online education you were already in the middle of.

Now, I know you’ve been waiting for it, so here’s the details on those  bees drinking from your eyeballs. There are three species of bees that appear to have evolved to drink human tears. It turns out that bees seem to benefit  from the proteins in our tears, which have more than 200 times  more proteins than our sweat.

So these bees are seriously  out-thinking pesky sweat bees. Because these tear-drinking bees  experience similar benefits from lachryphagy as other bees get  from pollen, they have evolved to drink our tears instead of or  in addition to collecting pollen. One researcher was so confident that they let bees drink their tears  and published the results!

And don’t worry, these bees  aren’t the stinging type. Now I know we’ve been calling it tear drinking, but in this case, it’s also tear storing. When the bees collect your tears, they actually store those tears… in their butts.

Okay technically the tears  go into their metasomas, which is their furthest back body segment. Their metasomas can expand up to 5 times the usual size when they drink tears. The bees then empty the junk outta their trunks and dump it into storage pots once they get home.

And the bees preferred human  tears over nearby dog tears, but since some did still visit the doggy eyes, bee lachryphagy probably expands to a bunch of different mammalian hosts. On top of the special stingless  bees drinking human tears, regular old hairy-legged bees have been observed drinking iguana  tears, which researchers think supply the bees with sodium,  potassium, and proteins. So it kind of seems like drinking tears is all the buzz in the bee community!

Overall, there’s still a lot to be learned about lachryphagy and why animals do it. But we do know that tear-drinking supplies crucial nutrients to feeders from  the most unlikely of sources. So the next time you’re  crying over a broken heart, bee on the lookout for  hungry bugs ready to pounce! [♪ OUTRO]