Every once in a while, I get a text out of the blue from a friend with a question about the ocean. When you work in ocean conservation, you get used to it. Sometimes I have the answer, but the best questions leave me stumped and send me down a research rabbit hole full of fascinating facts about our ocean’s coolest creatures.
My friend Biz posed one of those questions. She was watching a presentation by a shark scientist and a kid asked “do sharks sneeze?” It stumped everyone there and I admit it also stumped me. It was time to get out my magnifying glass and deerstalker cap and get to the bottom of it.
Love our content?
Sign up to never miss an update!
First, we need to define sneezing. A sneeze is a sudden burst of air up from your lungs into and out of your nose and mouth. In humans, we have something called a trigeminal nerve in our nose that is linked to the “sneeze center” of the brain. If something nasty irritates it, it tells the brain to sneeze. Our eyes shut, our face muscles brace themselves and ACHOO! That gust of wind comes flying out, attempting to clear whatever was bothering our poor little snoot.
Other animals sneeze similar to us, just watch this compilation of videos on YouTube. Seriously, this will add so much joy to your day. You’ll see that birds do it, bears do it, tigers do it, elephants do it through their big trunks, you’ve probably even seen your pets do it at home.
There are even some ocean animals who expel unwanted substances from their nose. Take the marine iguana who blows out salty snot rockets that you should definitely read about. Whales pushing water out of their blowholes could be a considered a kind of controlled sneeze that expels water, air, snot and, in the right light, rainbows.
So, what about sharks? Are they part of the lucky few who get to sneeze? Well in order to sneeze you need 1) a nose and 2) air to expel out of it. Sharks do have nostrils, but unlike humans, they don’t serve the dual purpose of smelling and breathing—instead sharks breathe through their gills. Their noses don’t connect to their throat like ours do nor do they have lungs. This means while they have noses, they can’t use air to force unwanted stuff out of them. Sorry folks, sharks can’t sneeze.
Now I know what you’re going to say, “Robyn! I saw a shark sneezing on YouTube. It must be true! The internet doesn’t lie.” And if you said that, you would be correct there are videos of sharks “sneezing,” but in reality, they only look like they’re sneezing. What they are actually doing is even more fascinating.
Videos like this most likely depict sharks trying to clear their throats or reset their jaws. These behaviors could also be a process called gastric eversion. Sharks eat a lot, including items that their stomachs can’t break down like bones, feathers and shells. This unfortunately also sometimes include man-made objects like fishing gear or plastic. To get rid of these items, sharks will cleanse their stomachs by literally vomiting their guts out to rinse out their stomach. Their stomachs are actually outside of their mouths for a moment before they suck it back in free of its contents.
Just because a shark doesn’t sneeze doesn’t mean its snout is useless. A shark’s nostrils, called nares, are powerful tools for sniffing out prey or their mate. Their nares contain the olfactory epithelium, sensitive cells that can detect tiny amounts of certain chemicals in the water. The myth that sharks can smell blood from millions of miles away is not true, but a lemon shark might be able to sniff out a bit of tuna oil in a backyard swimming pool. Unfortunately, ocean acidification might make it harder for sharks to sniff out food. It’s vital we protect our ocean to protect a shark’s powerful snoot.