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In these videos:

Soy sauce is poured onto a squid and its tentacles start waving around. Lots of the comments on YouTube as well as reddit state that:

  • The squid is already dead
  • The reason the tentacles move is because of salt, i.e. similar to frogs legs or sannakji.

Most of the mantle has been removed, but if you look at squid anatomy it is possible the brain is still intact.

Is the squid dead or not?

Brythan
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  • Yuck! That's barbaric, and cruel if the squid actually is alive and reacting to pain! (_+1 for a good question, but I'm not sure I have the stomach to return to read the answer._) – Randolf Richardson Nov 24 '11 at 18:24
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    Whether or not the brain is there is somewhat irrelevant to determining whether it's dead. Organisms as complex as starfish do not have brains but are still alive. On the other hand, I suspect most animals keep their brains more or less attached long after death. And even for organisms that normally have brains, most of it can be removed while the remainder of the biological systems continue working normally, a state most people would identify as "alive." –  Nov 25 '11 at 22:36

2 Answers2

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It's hard to source these claims scientifically, but let me try anyways.

In the following picture, the brain is below the tentacles and the eyes: A Squid (Source: http://en.wikipedia.org/wiki/File:Cephalop.jpg)

In all of the mentioned movies that part is gone.

The brain is gone in all of the videos, so the squid is definitely dead. So why does it move its legs? Just recently, Dan Lewis from "Know I Know" described why:

[...] The squid’s cells still contain some unused adenosine triphosphate (or ATP), which powers muscular contraction and expansion and, therefore, movement. But ATP can’t simply act on its own accord — it needs something to make it go. Typically, that’s provided by the central nervous system, which, through electrical impulses, causes the ATP to do its thing. With no brain involved, the ATP just sits dormant, and, over time, dissipates, as the now-dying cell fails to create new ATP.

But the soy sauce makes the typical atypical. Soy sauce contains sodium and potassium. The sodium and potassium ions together work as a trigger of sorts, causing the ATP to contract and expand the muscles. The result: a dead, dancing squid headlining (and, perhaps, ruining) your meal.

(Source: http://dlewis.net/nik-archives/dead-squid-dancing/)

Community
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Andreas Arnold
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  • +1 for an excellent explanation that also puts my mind at ease knowing that the creature isn't feeling pain. (_I returned on an empty stomach just in case though._) – Randolf Richardson Nov 25 '11 at 08:31
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    I found the "above the eyes" comment confusing, given the unlabeled picture was "upside down" (if that is a sensible concept for a squid). – Oddthinking Nov 25 '11 at 11:45
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    You are of course right. I rephrased that sentence so it makes more sense given the picture. – Andreas Arnold Nov 25 '11 at 12:50
  • @Andreas, thanks very much - I've been trying to find an anatomical diagram which supports what you've said but not been able.. –  Nov 25 '11 at 13:10
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    This answer doesn't source the assertion of where the brain is located. All the diagrams I've been able to locate show the brain *directly between* the eyes, and I don't see evidence the food preparation removes that part. – doppelgreener Feb 05 '17 at 13:04
  • Squids and octopi have lots of neurons in the tentacles, not just in the brain. This enables the tentacles to move autonomously in the live animal - and presumably also if the brain is removed so the animal is "technically" dead. – hdhondt Sep 03 '17 at 06:49
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Here is an MRI of a cuttlefish. Many people seem to mistake its body for its "head", since the tentacles look like legs, so the opposite of the "legs" must be the head, but the portion that is removed in the videos actually contains things like stomach, heart, etc. The brain is located between the eyes, so unless it was removed some other way it would seem to be there: http://csi.whoi.edu/media/cuttlefish2D

Mocha Matcha
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    [Welcome to Skeptics!](http://meta.skeptics.stackexchange.com/questions/1505/welcome-to-new-users) This reference is asking a lot of the reader. I am not able to recognise the brain in that scan. Are you able to find some anatomical diagrams that explain what we are looking at? – Oddthinking Sep 03 '17 at 07:07
  • Hmm, the video isn't animating for me. Is that part of the problem? – Oddthinking Sep 03 '17 at 07:08
  • I would also find this more on-point if it explained why the question says squid but this answer says cuttlefish. And in general, you might find the answer more effective if it took images from the original video and drew circles marked "brain here", etc. – Brythan Sep 03 '17 at 07:12
  • The 'answer' also does not explicitly yes or no. –  Sep 03 '17 at 08:41