The SQUID, Ego, and Superego....

Dec 24, 2002
Hi, I have a question about cephalopod neurology... From what I remember from invertebrate zoology cephs don't really have a "brain" per se, but a network of connections between their crainial nerves that serve as a very effective brain, right?

The other molluscs classes don't show that type of advanced neurological development, so I was wondering as to any theories on Ceph neurology and it's evolution. I think that, given the bauplan of the basic ceph with its chromatophores, individual arms, complex sensory and advanced optics (to name a few of its systems) needs a complex "brain" to keep things running.

Yeah, I'm stating the obvious here.

Soooo.... My question is this: Just HOW complex is the Ceph brain? I mean, do they have a psyche of sorts? How interconnected are the crainial nerves? Do they function like our corpus callosium? Can Cephs remember individuals? Can they alter behavior easily to adapt to new situations? Can they reason?

*sigh* I really wish I could work with them...

Sushi and Sake,

Re: The SQUID, Ego, and Superego....

Fujisawas Sake said:
*sigh* I really wish I could work with them...

John, I think you should :smile:

Right now, something like 10.15pm, surrounded by papers by J.Z. Young on ceph brains, those of J.B. Messenger on learning in cuttlefish (Sepia), and those of memory by G.D. Sanders (all bound up in a rather neat book titled 'The Biology of Cephalopods', eds M. Nixon & J.B. Messenger), in addition to a ton more, I'm sure if I could absorb it all I could answer the question .... but I'm afraid I just might fall asleep in the process (the book is 615pp). Give me a few days to study, then compose something succinct and I'll get back to you.

Is a 'corpus callosium' anything like a bunion on the brain? I think I have one of those.
Re: The SQUID, Ego, and Superego....

Steve O'Shea said:
Is a 'corpus callosium' anything like a bunion on the brain? I think I have one of those.

Actually, its a newtwork of neurons that connect the two hemispheres of the brain. It actually functions crosswired, so the right side of the brain controls the left side of the body, and vice-versa.

Thanks for the info. Animal behavior is such a weird subject to study, mostly since Zoologists and Psychologists seem to be quarreling about exactly under WHOSE jusrisdiction this science falls. I have no frame of reference about Ceph brains except my invert zoo and neurology notes.

My wife and I are in Texas right now, and we'll be flying back to Northern California on Wednesday. Maybe we'll go see if Telonicher Marine Lab is still harboring that dofleini... I've been trying to see if anyone there would post on TONMO, but so far, no luck...

Hi John,

not too sure about the corpus collsium question (I'll leave it up to Steve to research that :biggrin2: ) But certainly I reckon that cephs (octis at least) can reason!!

This is purely my own opinion but is based on a number of years looking after them in our public aquarium (mainly Pinnoctopus cordiformis) We had one who figured out that if you squirt the light socket with seawater you blow the bulb, OK I know that chance would have been involved in the first place, but that octopus sorted out cause and effect and fairly soon we couldn't keep the tank lit.

Another, used to go across to an adjacent tank and dine on the spiny rock lobster (Jasus edwardsi) nothing unusual in that I hear everyone say, true enough but it had the security check schedule figured out and it was ALWAYS in it's own tank by the time the curator made the 10.30pm check (until the evening he came in at 10pm and caught him in the act!).

This behaviour varies from individual to individual of course but on the whole this species usually figures out how modify it's environment to suit itself. Our current one for example, doesn't like the nice den we built for it so it's spent the last week pulling the morter, glue and fibreglass that we used to hold the rocks in place in it's tank and has used it's own personally selected rocks to create an new living area, apparently the loose rocks and terracotta planters we put in for it just were'nt suitable!!!). To my mind these are all forms of reasoning the octopus in each case has had to learn something that wasn't immediately obvious.

My 2cents worth anyway!


This response is going to come in installments, and a lot of what might get posted initially might go over your head (as it does mine) - it is not an area that I'm overly familiar with.

First things first, however, I'll cite a passage from Young, J.Z. 1977, p. 378 from a paper titled 'Brain, Behaviour and Evolution' (in a book titled 'The Biology of Cephalopods', eds Nixon & Messenger); most citations I'll give subsequent to this will be from this same work. This is something readily available to me - I'm sure there is more recent literature - but it is not something that I follow (so if I get something wrong please don't shoot the messenger).

We'll need an illustration or 2 in the near future to make sense out of all of this.

Characters of the brain of octopods and decapods (squid)
In squid the lobes of the brain are widely separated, there is no elaborate inferior frontal system, the ventral magnocellular lobe is large and there is often a system of giant fibres. Conversely in typical octopods the brachial and superior buccal lobes are joined to the brain and there is a large inferior frontal system concerned with touch discrimination and memory; there is no ventral magnocellular lobe or commisure and no giant nerve fibres; the brachial lobes are joined by a suprabrachial commisure (which is absent in squid). Many of these characters are related to the nektonic life of squid compared with the benthic one of octopods (but is variously modified in members of each group that depart from the typical mode of life).

The nervous system of cirrate octopods shows several primitive features: the supraoesophagael lobes are very different from all other octopods; giant nerve fibres also occur, suggesting that cirrates show an early stage of divergence of octopods from squid, perhaps not long after the stage represented by Vampyroteuthis. The presence of several anticristae in the statocyst agrees with this, and the absence of a chiasma of the optic nerve fibres seems an exceedingly primitive feature, otherwise known only in in Nautilus.

Haven't answered any of your questions yet John, but we'll get there eventually (and probably edit these posts as I go along).

I don't think there's much doubt that squid and octopus have memories ..... but we'll get to that in due course.
Thanks for the info Jean! Behavioral quirks are always fun to study!


Not completely over my head (though I've only studied HUMAN brains at length), but still really tough. Luckily, I know a great biopsych teacher who can translate the parts I don't completely undertstand.

That makes sense though. Apparently, the cranial nerves have formed into a pretty darn advanced brain. I would have guessed the sensory systems would be based on touch, taste, and sight, though considering that the squid is the molluscan answer to the raptorial predator I would assume that vibration would fit in (like a fish's lateral line array). As far as memory is concerned, that makes sense too. I guess I'm trying to form more of a ceph brain map than anything else.

Schweet deal... I should go book shopping. I am working on a mammal guide to help my wife out with her mammalogy class. Sometimes I hate phylogeny :lol: ... Just kidding, but it beats cladistics to a bloody pulp.

"CETIARTIODACTLYA"??!?!? :shock: Just shoot me and feed me to an Archi... Give me an Enteroctopus any day... or at least a Cryptochiton :lol:

Sushi and Sake,

The brain, eyes and statocysts certainly appear best developed in shallow water species/those in varied and well-lit conditions, such as Sepia and Loligo, and those with a very active life style (such as ommastrephid [= arrow] squids). The paper in question (J.Z. Young) details brain morphology and structure across a wide variety of squid and octopus taxa, from the abyssal to the shallow, benthic, benthopelagic and pelagic .... . The structures are very variable, and do appear linked to the life style of the animal. All rather fascinating actually .... but exactly how to do a synopsis of this in a few paragraphs is what I am battling with right now. Makes me want to go and do a few dissections actually .... it's always something I've just 'snipped' when doing anatomical work as it encircles the oesophagus (and habitually, but probably not necessary, I remove the alimentary canal in entirety to illustrate it/tease the structures apart; obviously I'll need to change my techniques).

I'm not mad keen on cladistics myself; I find assessing character polarity a rather difficult exercise. I'm at a loss when it comes to a link between Cryptochiton and Enteroctopus though ..... apples and oranges.
Cheers, O
'Behavioral quirks are always fun to study!' said Fujisawas Sake.

:lol: My cuttlefish started spraying water out of the top of their aquarium when they were hungry. They all seemed to do this within a week of each other. And although accidently at first they became accustomed to being fed when they did this. I actually put a stop to it when i got a 3 foot ink splodge down the wall and later they almost killed me when i was doing a water change. I was holding onto an electical extension while plugging in a filter or something and they spat water at me which all landed on the sockets i was holding!

LOL - how do you discipline a squid? Bad squid, bad squid :twisted: , spank, sizzle, yummy!
Fujisawas Sake said:
Schweet deal... I should go book shopping.

You might want to check out this book. It offers a summary of research on ceph behaviour (at least research as of 1996). It's written well enough that you don't have to be a full time cephalophile to understand it and it's got a huge reference section if you want more detail. It's the best cephalopod book I've been able to find so far.... not that I've been able to find that many.

Specifically, there are a couple of sections in the book that address your specific questions about the complexity of the brain and experiments that have been done on learning and memory. One interesting theme that seems to have come up several times is the apparent disconnect between the tactile and visual parts of the brain (at least in octopods). Anyway, I've been entertained by the book.

Another worthwhile buy was the title, 'Communication and Noncommunication by Cephalopods' by Martin Moynihan.
I managed to get it second hand via and it took about 2 months or so to get to me.

It is very well written and goes into detail about the senses, behaviour and learning processes.

Budelmann, did (is doing?) some interesting work on ceph sense organs, I seem to recall that using electron microscopy he found structures on the arms of young squid that look similar to a fish lateral line. Naturally, I can't find that particular ref! but others that are interesting are;

Budelmann, B. U. (1994) "Cephalopod sense organs, nerves and the brain: Adaptions for high performance and lifestyle" Marine and Freshwater Behaviour and Physiology vol 25, p. 13-33

Budelmann, B. U. (1996) "Active marine predators: The sensory world of cephalopods" Marine and Freshwater Behaviour and Physiology vol 27, 59-73

I found them to be very interesting. I have to confess that in a previous life (ie before grad work) I was a psychology student, primarily looking at behaviour and neurophysiology, then I came to my senses but every now and then I have a relapse :madsci:

Wow! Thanks for all the helpful tips! Hopefully I can find these books...

Oh, and Steve, the Cryptochiton reference was because the Gum Boot Chiton was my first intertidal animal discovery. I had absolutely NO idea what it was at the time. They still remain one of my favorite seashore creatures.

Btw, my second was an O. rubescens, follwed by a moon snail. So I'll always have a soft spot in my heart for molluscs.

Guy you have the right person to answer this question. Well Cephalopds do intact very well have a brain but there brain is surprisingly not that very well big. So small I couldn't even find it when Dissecting a Squid. Like humans Octopuses are very smart and intelligant creatures actually the most intelligent mollusk species ever. Humans use there brains which have nerves to send them but Octopus on the other hand have so many nerves in its body than in its brain. Octopus have so many nerves infact its almost like an Octopus's body actually controlls itself and thats what makes the Octopus so strong. An Octopuses most sensitive nerves are its suckers which are located under the arms of an octopus and each arm holds about over 240 of them. Each sucker on the arm actually has a small brain like cell called somthing that starts with an f i think. Each of these little brain cells in each of its 240 suckers can smell, taste, and sense MANY things. They can even detect tell taled chemicals in the sea. Also the suckers are incredibly stron and when they cling on to you there very hard to get off of. Since an Octopus has so many nerves it has very low stamina and will tire out easily. Since it has low stamina they have 3 hearts in its body one to pump its gill, one for pumping blood, and another one to pump all around the body or nerves.
Armstrong said:
Each sucker on the arm actually has a small brain like cell called somthing that starts with an f i think.

It's on the tip of my tongue

...I'll go and get a book :lol:

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