So it's been a while since I've seen the Nightmare Before Christmas, but it's come up in my thoughts recently. Or at least one specific background character.

Harlequin Demon from The Nightmare Before Christmas


This character is apparently called the Harlequin Demon. As you can see, instead on a mouth that uses a hinge joint, this guy has a ringed mouth that encompasses the circumference of his head. If you haven't seen the film, the rod connecting the top and bottom parts kind of moves the upper cranium up and down and that's how he talks. What would that even be, a piston joint?

When I was looking up references on how a radially symmetrical mouth would work, my mind ended up going to this weird looking design. And then I realized that it's kinda impractical.

That rod between the top and bottom part of the head likely contains the spinal cord. I don't know any way to make the spinal cord stretch up and down like that without damaging it.

Not to mention the potential difficulties with swallowing, breathing, and the fact that the spinal cord is now much more exposed and having to support the entire weight of the brain and top half of the head with no visible muscular support.

Now I'm wondering this: How can a mouth like this actually work?

(As in, how does it move up and down and not instantly snap off from the weight of the upper cranium. Breathing and eating I think could be possible, but somewhat challenging.)

  • 1
    $\begingroup$ Well, while indeed they don't have to endure the stress of having to push the top of the head up and down (and presumably at high speeds if you want your creature to be able to crush food properly), the cervical vertebrae of our spinal column are directly connected to our cranium. They generally do fine supporting our entire skull, brain and jaw even if they're only about an inch or so in diameter. It's not so much the weight that's going to be the problem but rather wear and tear due to motion. $\endgroup$
    – AngelPray
    Oct 16, 2017 at 21:50
  • $\begingroup$ @AngelPray Actually it occurred to me that he could probably use the two parts of the mouth in a sawing motion, but that might be even more energy spent chewing up stuff. $\endgroup$ Oct 16, 2017 at 21:52
  • $\begingroup$ have you seen a pelipper... pelican? sorry too much gaming for me. $\endgroup$
    – user6760
    Oct 17, 2017 at 2:44
  • 1
    $\begingroup$ @user6760 Pokemon is its own weird branch of biology. $\endgroup$ Oct 17, 2017 at 2:46
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    $\begingroup$ Someone flagged this as off-topic and I can't understand why. This is a perfect creature-design question and I am voting to Leave Open. Please state your problems with questions when flagging and voting to close so that the OP can fix any problems that might be there. The OP can't fix anything if they are not aware of any problems. $\endgroup$
    – Secespitus
    Oct 17, 2017 at 11:34

2 Answers 2


The Head's Just for Show

The brain is not actually in the top part of the creature; in fact, very little is. The brain and actual eating apparatus are both in the over-large body cavity. The "head" is an appendage used to frighten other creatures, but serves little other purpose. A muscle connects it to the rest of the body, and the muscle can be flexed to make the "head" go up and down. A bundle of nerves that goes from the "body" to the "head" also fire signals that make the "eyelids" blink randomly (I like to think continuously, even when sleeping). The external "fur" and "scales" are in fact sensors that this blind creature uses to understand and interact with the world.

When food is placed into the apparent "mouth" the muscle that connects the "head" to the "body" begins firing. Although the food may be somewhat crushed in the act, the true purpose is to push the food toward the hole that leads to the true digestive area in the body. Which is, appropriately and frighteningly, filled with teeth.

Just as frightening as the creature with its head is what it looks like without it. Because, being an appendage made only to frighten others, the creature can live without it.

  • $\begingroup$ Also very creative! $\endgroup$ Oct 17, 2017 at 2:02

All the important parts are on the top side. The lower part is a growth from an arm like appendage extending from the creature.

The bottom is for storage, locomotion and manipulation, but the circulatory, respiration and primary digestion are all above. Those striped protrusions absorb oxygen and by moving pump blood.

It eats using a sifting motion like panning for gold. Prospective food is passed over the visibly smooth lower pallet in a circular motion, a not pictured tongue on the roof of the mouth aids sorting pushing undesired pieces through the teeth and moving desired pieces into the digestive system above.

It mainly feeds on rotting pumpkins so digestion is much simpler than in creatures breaking down the food internally. During the eating season (October and November) it gains more than ten times it's weight (pictured in late fall around maximum) storing calories to last the rest of the year. The 'body' is non-essential, and in case of breakage the primary organs can detach use the upper teeth for locomotion and regrow the lower part.

The head doesn't actually move while talking, the soft parts of the lower side of the mouth open wider and the whole creature bobs on its feet, which just looks like the lower mouth and chest stay still while the top mouth moves. The air used to speak is not from it's lungs but entirely in the mouth requiring the bobbing motion to get enough bellows action.

  • $\begingroup$ I like the creativity here. $\endgroup$ Oct 16, 2017 at 23:16

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