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You can get a $100 60-day credit on a new Linode account at linode.com/scishow. We all sneeze now and then, whether it’s a quiet a-choo or a thundering roar.

And like it or not, sneezing does serve a purpose. Basically, your body is trying to kick whatever is irritating you to the curb by spewing air and bodily fluids out of your nostrils and mouth. And that could be allergens or a seasonal bug.

As it turns out, underwater animals need to clear their openings, too; sometimes for the same reason as us, and other times for very different purposes. And when they sneeze, it can look pretty different from ours, because, well, they’re underwater. I mean, some animals, like sponges, don’t even have nostrils in the first place!

From half-hour-long sneezes to life-saving snot, welcome to the bizarre world of underwater sneezing. [♪ INTRO] While we might be the only ones following up with a ‘bless you’ or a ‘gesundheit’, humans didn’t invent the sneeze. Lots of other animals sneeze too, from cats to rats. But sneezing underwater is a whole different ball game.

Like, think about sponges. They’re some of the geologically oldest organisms on Earth, and they sneeze. In general, the life of a sponge is pretty chilled out.

Drawing water in through their pores, they take in everything from phytoplankton to viruses. As expert water sifters, their specialized filter-feeding cells pick up any tasty morsels they might want. But the leftover waste needs to go somewhere.

Enter the sponge sneeze. Its purpose is similar to our own, given that we both tend to sneeze to remove unwanted particles from our passages. But how they do it is wildly different.

Those particles are tossed out through the same pores they entered, where they’re picked up by a stream of mucus. Now that probably sounds familiar. But here’s where sponges kick it up a notch.

Their mucus flows across the surface of the sponge, forming rather perfectly named mucus highways. The sponge moves its mucus along its highway by contracting and relaxing its outer layer of cells in a wave pattern. Throughout this process, sponge snot builds up in key spots along the slime highway.

Then, more contractions result in those stringy clumps of boogers being shed into the surrounding water. And that whole process can take 20-to-50 minutes. And at least some species of sponge are kind of always in the process of sneezing.

Now, that’s a bit longer than the average human sneeze, but pretty much serves the same purpose. Like sponges, Corals need a way to get rid of unwanted sediment. They also create a mucus layer to help them sneeze out that stuff, trapping particles and sloughing them off into the surrounding waters.

Under normal conditions, corals are constantly making mucus in an extremely thin layer, so you could say that they’re basically always sneezing and you wouldn’t even notice it. But “normal” is a moving target, and these days there are way more particles stirred up by, well, us. So, yeah, we are making corals sneeze more.

Corals are not having an easy time in general, given the temperature increases and wide range of pollution we’ve been subjecting them to. And on top of that, they’re being served extra sediment from underwater dredging when we dig up the seafloor. So it looks like their extra snotty solution is a response that’s happening in stressful situations, most often within a short distance from dredging sites..

Now, it’s still not totally clear whether it’s mostly surrounding water doing the work to slough off the mucus or if corals are actually helping to push it away, similar to the sponge contractions. That said, they do do some expanding and contracting to shake themselves free of these contaminated boogers, so it appears they are in fact letting out their own version of a sneeze. While a lot of animals use sneezes to get rid of unwanted external contaminants, in some cases, like the hagfish, the need to sneeze comes from within.

Hagfish are pretty bizarre for a number of reasons. But they’re most famous for using full body booger production to fend off attacks. As a defense mechanism, they can produce a shocking amount of slime almost instantly, clogging up their attackers mouth and gills.

So hagfish are kind of the opposite of sponges and corals because instead of ejecting their mucus in a slow snot stream, it only takes a split second for them to make a bucketful. When threatened, they spew a concentrated concoction from slime glands down the sides of their body, which mixes with the surrounding saltwater to instantly make about a liter of impressive goo. While sponges can take the better part of an hour to get it all out, hagfish take a fraction of a second.

So in that way, hagfish are more like us. Except that it’s a full body event. And with so much mucus, their snot production puts even our most impressive sinus infections to shame.

But hagfish are in this video for more than that famous propulsion. If you wanted to be picky, you could argue that’s not a sneeze at all. But they let out something closer to a true sneeze, too, and this one actually involves their nostril.

And yes, I said singular nostril. They only have one. But really, one works just fine for them.

It’s not just their own slime they need to occasionally clear out. External irritants appear to trigger the single-nasal-sneeze, too. One study used dye to irritate their sensitive nasal passage, which triggered a sneeze within five seconds.

Though sometimes referred to as “nostril coughing,” researchers have stated that it’s really the same as a sneeze, so we can slot hagfish comfortably alongside the other underwater sneezers. Whether they're forcing out unwanted irritants or their own defensive goo, there’s a pretty phenomenal selection of creatures that find a way to sneeze underwater. And most impressively, they manage to pull it off despite lacking air-breathing lungs and in some cases, even nostrils.

Anyone else have the urge to blow their nose right about now? Now animals need to sneeze all over the world! Just like people need to access ground-breaking cloud computing technology all over the world.

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To get set up from anywhere in the world today, you can click the link in the description down below or just go to linode.com/scishow for a $100 60-day credit on a new Linode account. Thank you to Linode for supporting this SciShow video! [♪ OUTRO]