hi.
slightly embarrassed to be asking this question but here goes.. (i know nil about octopuses, though i plan to do something about that:)

i've been hearing these stories about octopuses having nine brains, -one "mainframe" and then 8 more, -one in each tentacle. however, i haven't been able to dig up any information on the web that confirms this claim.. well, not on any reliable sites at least. and it seems kinda too wild be true.. :shock: is this just a popular misconception stemming from the fact that octopuses seem to have more "decentralized" forms of control mechanisms and a complex nervous system, or is it actually a fact?

sorry for the ranting, i haven't got the foggiest about what i'm talking about,
please bear with a newbie :grin:

:welcome: to TONMO.

First off, that was a VERY good question.

Well, I wouldn't say nine actual "brains" per se, but there are clusters of ganglia in the arms that probably do a lot of sensory and motor processing on their own, reporting to the Central Nervous System and brain as needed.

A lot of people write about the many "brains" of octos. I think this is mostly to dazzle the laymen a bit. This article (http://news.nationalgeographic.com/news/2001/09/0907_octoarm.html), is a bit better, but what is really worth noting is that this adaptation is a lot like how our own vertebrate brain works; we have a lot of sensory and motor functions outsourced by the brain to the nerves. In no way am I trashing the aforementioned article; its just that we vertebrates do the same thing and tend to take it for granted. Makes we wonder who is convergent with whom...

Octos also have an actual brain, and a cartilaginous skull - this cephalization is a MAJOR adaptive change from other members of its phylum. The gathering and change of its cranial nerves into a brain offers an interesting look into its behavioural ecology and natural history.

THIS LINK (http://www.fortunecity.com/emachines/e11/86/cephpod.html) may offer some information.

Hopefully this was of some help...

John

:
and a cartilaginous skull

John
eh!? I thought that for the most part, octopuses were vitrually free of hard parts, 'cept those 9 spp of NZ octopuses?

But yeah, regarding the brains; they are ganglia, which are a swelling of the nerve bundles, if my memory serves me correctly. I expect that they can't use 'em to think, but the senses in the arms will be highly developed, as well as motor control.

Graeme- gah! tis too early for me... and I have to get on with my hons proj!:cry:

eh!? I thought that for the most part, octopuses were vitrually free of hard parts

hi!
i'm anything but well-versed in the terminolgy of bio-/physiology, but i thought "cartilaginous" meant exactly that it isn't hard but rather soft and tissue-like, as opposed to "calcareous"...?? :hmm:

Hopefully this was of some help...


it sure was, and thanks for the pointers, they made for some truly fascinating reading. one thing though, -am i right in taking what you said about octopuses here to also apply to cephalopods in general? (please pardon the noob factor :smile:)

eh!? I thought that for the most part, octopuses were vitrually free of hard parts, 'cept those 9 spp of NZ octopuses?

Yeah... cool, isn't it? In Invertebrates by Gary and Richard Brusca, the Brusca brothers mention a rudimentary cartilaginous skull surrounding the brain case. "Hard" or "soft" in this case is pretty much up to you, but its nothing that can hinder the octopus' movement much. It also should be noted that this level of cephalization is usually reserved for those animals needing to protect their brain! I think that's badass, considering that this is a mollusc.

hi!
i'm anything but well-versed in the terminolgy of bio-/physiology, but i thought "cartilaginous" meant exactly that it isn't hard but rather soft and tissue-like, as opposed to "calcareous"...?? :hmm:

err, yeah you're right, I feel really stupid now that I've actually read that word properly :oops:
Cartilage is, in fact, essentially soft bone that hasn't been calcified. Makes up a shark's skeleton. Why on Io did I think that it was a hard substance!? Oh well, must've been the day I was having...:razz:

Graeme

Yeah... cool, isn't it? In Invertebrates by Gary and Richard Brusca, the Brusca brothers mention a rudimentary cartilaginous skull surrounding the brain case. "Hard" or "soft" in this case is pretty much up to you, but its nothing that can hinder the octopus' movement much. It also should be noted that this level of cephalization is usually reserved for those animals needing to protect their brain! I think that's badass, considering that this is a mollusc.

wow! Could this indicate some sort of (almost) higher intelligence? Sure, it's well known that they can problem solve etc, butcould the need to protect its faculties mean that it's maybe on par with most decent-sized mammals? I dunno- too early in the morning for me to make sense!

Graeme

... I dunno- too early in the morning for me to make sense!

Graeme

Mate, it was 09:59 (UK) when you posted that! I'm impressed.:lol:

I failed to launch significant interest in the "recently" discovered mimic octupus in another thread :wink: so maybe this one might pick up on it, as it's (a lot) less off topic here. :oops:

http://marinebio.org/species.asp?id=260

http://www.oceanfootage.com/stockfootage/Mimic_Octopus/

If you look at available footage on the web, it is uncanny how "ambidextrous" this little octopus is, each arm feeling it's way around the surface clearly gives off the impression of a dedicated neural circuit governing each, whereas the mimic behaviour halmarks an impressive level of integration at the behavioural (central) level. The only thing that gets me is that with molluscs, the smarter they get, the more shortlived they seem to be, in total contrast to vertebrate analogies. Clams may grow to well over a hundred years, whereas the average cuttle or octopus doesn't make it past two. :boohoo:

Mate, it was 09:59 (UK) when you posted that! I'm impressed.:lol:

Aye well, I'd been in uni since about 20 past, so it's not really that impressive, but my brain doesn't quite kick in til about 10, back of 10, unless I NEED to be in for 9, then it's pretty much ticking away at... oh... 9:20! :lol:

Oh, the joys of higher ed!

Graeme

am i right in taking what you said about octopuses here to also apply to cephalopods in general? (please pardon the noob factor :smile:)

You know, I'm not really sure about the squid, so I would have to answer "no" to that at the moment. Steve O'Shea might be a better resource for that.

John

wow! Could this indicate some sort of (almost) higher intelligence? Sure, it's well known that they can problem solve etc, butcould the need to protect its faculties mean that it's maybe on par with most decent-sized mammals? I dunno- too early in the morning for me to make sense!

The trend in evolution, especially where cephalization is concerned, is that when more resources are concentrated towards the formation and maintenance of a "brain", the result will also lead to a means to protect said brain. I honestly think that intelligence is a side-effect, or result, of having a more centralized brain and greater processing capability, but that's only my opinion.

Yeah, I get the impression that octos may be pretty smart; perhaps on par with some mammals, but how to accurately measure that level of intellect is beyond me.

But if intellegence is a side-effect, then why bother maintaining the brain and "upgrading" it to work more? Evolution is a weird thing. Could it maybe be that cephalisation and growth of "intellegence" go hand-in-hand? I know that the probable reason for cephalisation is probably to develop the senses, but there needs to be something to keep on par with the senses in order to be able to process them, and define them.
Yeah, Cephalopods are smart, no doubt about it (especially octopuses), but I reckon that their display of it is so alien that maybe we can't ever understand. Put it this way, sure they can manipulate objects etc, but can you imagine trying to pick up and move, say, a stone with a long flexible arm instead of what we have? it'd be just a bit weird for us to comprehend, I reckon. This may come out a garbled rubbish, but it's difficult to try and convey what I'm trying to get at. They truly are an alien organism, eh?
Graeme

Just a point of clarification: what do you mean when you say "cephalization"?

Cheers!

It indicates the headward tendency of parts in phylogenetic development; the tendency of the centers to move forward, and of organs to become innervated from centers more anteriorly placed. From cephalon, (latin for) greek for head, as in: cephalopod ("Head foot") or encephalon ("in the head"; brain).

Just a point of clarification: what do you mean when you say "cephalization"?

D'oh! Sorry... Should have clarified a little...

It indicates the headward tendency of parts in phylogenetic development; the tendency of the centers to move forward, and of organs to become innervated from centers more anteriorly placed. From cephalon, (latin for) greek for head, as in: cephalopod ("Head foot") or encephalon ("in the head"; brain).

I thought it always meant "the formation of a functional head"... Meh, must be the studenty description... with finger puppets and all!:lol:

Graeme

Get carried away sometimes on precision...

Asperger? :confused:

Nah, dude. That's a good thing. It gives us so-called studiers of zooness a kick up the proverbial jacksie into using beter definitions.

Hans Asperger? :confused:

Graeme

I know it is way too soon but i would like to see studies on whether the mimic's behaviours are learned or instinctive.

Mimic octopus?? Well, as far as I know, the word mimic implies a "monkey see; monkey do" style of immitation. Whether the term is accurate or not, I don't know. I would guess that it's a learnt behaviour.

Graeme

Hans, indeed... Anyway: the ability to learn how to imitate may be instinctive:)

My favorite remains the mantis shrimp

Are you sure? I thought that imitation was an observational behaviour, damned if I can remember all the terms (and I should!!) but I was under the impression that imitation wasn't hard-wired. But then I guess the Natural World keeps throwing up things just when we think we understand something! Keeps us occupied I s'pose! :grin:

Graeme

If "hardwired" behaviour turns out to be succesful in the survival game, it's nothing else but fitness and therefore perseveres in the genepool. Same goes for eyespots on bimacs, the "twig in a breeze" movement of chameleons or the ability of mimics and (likely) wonderpusses to observe and imitate. The imitation itself is based on the input of the moment and interpretation of events ("I see territorial damselfish, I must assume banded sea snake effect"), but again, the ability to perform the interpretation and act accordingly is the bit that's hardwired.

With (a two year lifespan and) no real parental care or social structure, there is not likely a meme based learning-process, as is with social animals such as our own species.

If the ability to mimic wasnt preprogrammed that would mean that there wasnt anything really separating a mimic from any other octo, there would probably be heaps of copy cat octos.
So the question is whether its repertoire is totally instinct, or if it learns the different imitations from experience. ie a mimic that had never seen a lionfish would never use the lionfish "ability". I would say its very likely the latter.


It would be a great thing to try figure out. I would imagine that the trigger for memorizing how to mimic objects would be black/white stripes.

Perhaps you might be able to get a mimic to copy something totally random, like a chess board or something. Just like ducklings following anything that waddles past when they are born in that famous experiment (cant remember by who)

Man ob that makes it more confusing. Do you think that the "repertoire" is totally instinctive?

I see territorial damselfish, I must assume banded sea snake effect"
Maybe it just uses a different ability from whatever it is being threatend by?
Does it do the same thing each time?

ob Your very well informed!!! :)

What's really the interesting bit, is that the mimic octopus mimics its predators' predators. Your observation with regards to there not being multitudes of copycat octo species is very astute! It is for all intents and purposes the strongest argument for a unique built in quality.

The repertoire is built on what works in practice, so as the Lembeh straight is home to lionfish, banded sea snakes, poisonous flounders, brittle stars and mantis shrimp, that's what gets selected for. The flounder and starfish patterns are the only cases where the mimic's behaviour is pure mimicry. It uses it when it is out in the open as to avoid being eaten.