linguist & software engineer in Lenapehoking; jewish ancom trans woman.
since twitter's burning gonna try bringing my posts about language stuff and losing my shit over star wars and such here - hi!
This is because, in a work of evolutionary WTF, their esophagus passes through the main nerve cluster that functions as their brain. Take too big a "bite"? well,,,
As it turns out, the circumesophageal nerve ring is found in several invertebrate phyla. I think this counts as "trick" in trick or treat, tbh.
Diagram from Invertebrate Zoology: A Functional Evolutionary Approach by E. Ruppert, R. Fox, and R. Barnes.
thank you for this extremely cursed fact
(though many other animals would probably consider human swallowing cursed--what do you mean you can't swallow and breathe at the same time?!? so if food gets stuck you just die???)
yeah you're welcome, I thought you specifically would enjoy how incredibly cursed it is 
the Wikipedia page isn't really telling me why those are a problem but I'm so curious! what goes wrong?
So besides the inelegance in any vertebrate with a neck of a nerve coming down and wrapping around the aorta to come back up and serve the upper throat, it gets worse the longer the neck is. In modern times, giraffes probably have it worst. This nerve now has to stretch over 7 feet down to the aorta, then 7 feet back up to just below the head. But Supersaurus is estimated to have needed a nerve 92ft long. (Only matched by the 98ft nerve that goes to the tip of the tail.)
It's also worth pointing out this means all the blood has to come through the top of the heart, through the aorta, around this nerve, and then to the rest of the body. This awkward bend in the aorta severely increases the possibility of aortic dissection, where the aorta bursts from some kind of stress and all the blood quickly leaves the arteries. (To be fair, the aortic arch also wraps around the air intake for the right lung, so maybe it would need to exist anyway, but this nerve certainly doesn't help. I haven't taken a look at the breathing fish, but I'm pretty sure this nerve detour predates lungs? And so may have created the arch?)
There's also a (fairly rare) medical problem in horses involving paralysis of the neck that's theorized to be caused by this nerve as a side effect of their incredibly strong hearts and fairly long nerve
