cephelopod brain anatomy

Discussion in 'Physiology and Biology' started by darwin4819, Apr 3, 2007.

  1. darwin4819

    darwin4819 Pygmy Octopus Registered

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    does anyone have any info on cephalopod brain anatomy and how it compares to mammal/vertabrate brain anatomy?

    and on a sillier note, me and a friend were having an argument about intelligence in animals and of course I had to bring up octopi and squid and he said that chimps are smarter because they can be taught sign language, but I think that cephalopods could learn sign language but they don't have fingers (although eight arms could be an advangtage...) and commucating with color :rainbow: is so much cooler

    so what do y'all think...who is smarter a chimp or a cephalopod?

    okay well I guess that's enough of a tangent, sorry for the sillyness :razz:
     
  2. WhiteKiboko

    WhiteKiboko Colossal Squid Supporter Registered

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  3. monty

    monty Colossal Squid Staff Member Supporter

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    Well, I took a whole class in comparative nervous systems, that covered a week on octopuses and a lot of various vertebrates, and I've got a few books handy. There are a number of other folks around who do this professionally, though, so I'm far from the best qualified one around, too.

    What in particular did you want to know? Here are some random facts:

    The brain surrounds the esophagus in cephalopods, so if they don't take small bites of their food, they can wreck their brains. In general the brain is donut shaped, with a number of lobes. The brain areas in cephalopods are rather different than they are in mammals, so there aren't the usual brain areas like "cerebrum/cortex," "cerebellum," "brain stem," and "hippocampus." There's also no "white matter" because cephalopods don't have the white myelin sheaths on long nerves like vertebrates do. This means that when squids need to send a signal a long distance quickly, instead of having a myelinated nerve, they just have a much bigger nerve. That makes the "squid giant axon" used in its escape reflex a great tool for biologists to study, since it's a lot bigger than most nerves, but is very similar in other respects, so it was where the model of how nerves work (called the Hodgkin-Huxley model) was developed, which is pretty much the foundation of modern neuroscience. Most cephalopods have a sophisticated visual system, and the visual lobes of the brain are a large part of the brain in most species.

    In terms of chimps vs cephs, I usually model cephalopods as being about as smart as cats, and I think most people would consider chimps smarter than cats, although I've known some pretty smart cats. But it's hard to compare cephalopods to other animals, because their nervous systems are so different. One reason I think it's very good to study cephalopods is that they are only distantly related to us, so their brains serve many of the same functions as ours do, yet they are very different in structure and development, so it's possible to learn a lot by comparing them to vertebrate brains to see where there has been convergent evolution, or where there are completely different solutions developed, and whether these can be explained by their different lifestyles or environments, or whether they're just accidents of history.

    Cephs are certainly very expressive visually, so in terms of the sign language comparison, I'd say that the fact that cuttles and reef squids communicate with gesture naturally in the wild might make for an argument that they're smarter than chimps, since they don't need to be taught! I do have to correct one thing: although cephs look colorful to us, and use color extensively in camouflage, they are almost all color-blind (except the firefly squid), so they don't use color to communicate with each other, just patterns, gestures, and, the really sneaky one, in the polarization of light, which us vertebrates can't see at all.
     
  4. DWhatley

    DWhatley Cthulhu Staff Member Moderator

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    And I thought Cephalopod Behaviour was expensive!
     
  5. darwin4819

    darwin4819 Pygmy Octopus Registered

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    thanks for the links whitekiboko, I'm a student so I wish I could afford that book but I kinda like to eat.. so I think I'm have to wait on that, the second link was great though

    monty, thanks for the random, facts that's just what I was looking for, I've taken several classes on vertabrate brain anatomy and physiological psychology (human brain anatomy) so since I'm interested in cephalopod intelligence I was just wondering how they related as far as the anatomy was concerned.

    It's interesting to learn that they are almost all color blind (I although I have to say that the polarization of light communication is even cooler), especially since they have such a large visual cortex, you mentioned that they use color in camoflauge and I've seen a video (sent to me through e-mail...I think from it was on youtube) of an octopus using color for camoflauge.... so this may sounds like a stupid question but if they can't see color how do they know what colors to mimic(not in the conscious anthropomorphic sense but what mechanism..)? or are they just using their natural colors with very clever shading?

    and I definitely agree about the evolutionary advantages of studying cephalopods and how they have developed characterstics analogous to vertabrates (I'm hoping to study that for grad school)

    thanks for the info
     
  6. WhiteKiboko

    WhiteKiboko Colossal Squid Supporter Registered

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    you might want to see if your school has cephalopod behaiour by hanlon and messenger... a more affordable choice and hence more likely to be in a collection...
     
  7. darwin4819

    darwin4819 Pygmy Octopus Registered

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    I'm sure most have seen it but here's the video that I was talking about showing the octopus camoflauge (gotta love youtube)

    http://www.youtube.com/watch?v=OQWxIrSRDQQ

    I will have look for the cephalopod behavior book, I thinkI'll have more luck getting a hold of that than the other one
     
  8. darwin4819

    darwin4819 Pygmy Octopus Registered

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