why-animals-do-the-thing:

This ask made me so happy, @tsaagan​, and turned out to be really fun to research. 

To address your question, we first have to figure out why getting water up your nose hurts! The short answer is: because the water in the epithelial cells that line your nose is way saltier than the water going into your nose, so the sudden osmosis that occurs when lower-salinity fluid comes into contact with those cells is distinctly not comfortable. (It also seems possible that some of the discomfort comes from the fact that there’s now something in contact with an area that doesn’t get a lot of tactile stimulus). The reason it hurts when water gets into your sinuses  - versus just touching your nostrils -  is that the epithelium inside your nasal cavity is pretty thin compared to what’s in the more distal parts of the nostrils, and while both areas are mucous membranes, the epithelium in the sinuses has fewer mucous producing glands. That means you’ve got more delicate tissue in that area, and less mucous around to provide a buffer between the cells and the invading low-salinity fluid. 

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While the epithelium of an elephant’s sinus cavity is somewhat different than a human’s, there are still enough similarities with regards to the presence of delicate mucous membranes and the salinity inside epithelial cells that I’m comfortable positing that yes, if elephants got water into their sinuses, it would probably be just as unpleasant for them as it is for us.

However! When elephants pull water into their trunks it doesn’t actually get far enough into their head to reach the sinuses - they’ve got a nifty muscular structure that lets them pinch their nasal passages closed before they enter the skull. (Now, this isn’t to say that a super-fresh baby still learning how to navigate having a trunk might not hypothetically mess up and suck water into it’s face too hard, but shutting off those passages is likely a reflexive action for adult elephants). Here’s a diagram of that structure from one of the most useful elephant textbooks I’ve ever encountered:

(Image Credit: Biology, Medicine and Surgery of Elephants, 2006; p292)

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Now, as to the booger question, that’s pretty situational. In general, an elephant’s trunk isn’t snotty even though it’s lined with a mucous membrane: the pink tissue lining it is pretty similar to the inside of your lip. (Actually, it’s very similar - an elephant’s trunk is basically a fusion of their nose and upper lip.) There is mucous secreted from the lining of the length of the trunk, but it tends to stay in one place; it plays a really important role in helping transport odor molecules to a specialized sensory organ near the base of the trunk. Here’s an up-close photo of that trunk tissue:

(Photo Credit: B. Beury)

According to Jessica, an elephant professional I talked to with over a decade of hands-on experience, it’s mostly the older elephants who end up with dribbles of mucous running out the end of their trunk. Our discussions again used the human nose as a comparison - there’s a ton of mucous up in our noses, but they don’t really run noticeably unless something is going on.

Because there’s a mucous lining in an elephant’s trunk, there will always be a little bit of mucous in the water they suck up into it; it’s just generally not going to be a noticeable amount - think similar to what you’d end up with if you swished water around in your mouth for a while. If they sucked water up super far into their trunks, though, and then blew it out super hard? That’s when you get a ton of boogers. And sometimes, in human care, that’s actually exactly what we ask them to do.

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Tuberculosis can be a problem with elephants in human care (a lot of the Asian elephants imported decades ago had picked it up from their handlers) and it’s a hard disease to test for in elephants because they’re literally too wide to get a clear x-ray of their lungs. The animal management world has solved this problem by creating something called a “trunk wash”: when an elephant holding a trunk full of water breathes out forcefully, any bacteria expelled from their lungs gets trapped in the water and can be detected in a lab. There’s a great video of a whole trunk wash behavior at 3:50 in this clip, from Wildlife Safari in Oregon - you’ll have to click through to watch it because it’s a Facebook video. If you can’t watch it, here’s how it works: a syringe full of sterile saline is emptied into one nostril of the elephant’s trunk, and then they’re asked to raise their trunk up high (to ensure it gets right up to that point where the nasal passages are closed off) and hold it there for a bit. Then the elephant lowers it back down, the keepers place a plastic bag over the end of the trunk, and the elephant blows all the water out into the waiting container. The whole baggie - water, snot, and all - is given to the veterinary team, and they’re able to test it for the presence of tuberculosis bacteria. (Why is a trunk wash only done with water in one nostril, you ask? Since the two nostrils in an elephant’s trunk are separated all the way up, if something goes wrong with a trunk wash procedure… like an elephant deciding to drink and/or spray the water out instead of putting it in the sample bag… you’ve got another nostril ready to go!) In lieu of a good photo of the steps of a trunk wash, here’s a great photo I was sent of an elephant filling only one side of it’s trunk from a spigot:

(Photo Credit: V. Gagne)

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TL;DR: Elephants don’t get water in their sinuses when they use their trunk to drink because they’ve got a nifty muscle that lets them close off the base of their nasal passages, but if they didn’t utilize that muscle, it would probably suck just as much for them to get water “up their nose” as it does for us. When they blow that water back out, it’ll normally have a little bit of snot in it, but if they exhale super hard it’s totally full of boogers.

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This post is part of the first Friday Theme Day on WADTT: Elephants! Stay tuned throughout the day for more elephant-related posts. 

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