Everyone knows cephalopods are tricky bastards. The coleoid cephalopods, anyway (squid, cuttlefish, and octopuses). I haven’t read any stories about tricky nautiluses, but if you find one, I’d love to hear about it.
Anyway. The coleoid cephalopods. They are sneaky predators. Octopuses apparently have been found to steal crabs out of fishermen’s crab pots. Some apparently use tools—veined octopuses have been documented gathering discarded coconut shells and constructing shelters from them (Finn 2009). (They took video of this, which you might be able to see here. You also might not, I’m not sure if you need subscription access, which I have through the U of M…sorry.)
Figure 1b from Finn 2009. Squee!
Sorry, I got a bit excited and distracted there. Back to the tricky bastards business. Octopuses in aquariums have been known to escape through tiny cracks, pull down lights, and open jars with twist-off lids. Humboldt squid might possibly coordinate to catch prey (I read this several places but could not find a reputable source for this tibdit.) Cephalopods are also good spatial and navigational learners. Claims have been made that octopuses have observational learning abilities as well (i.e. monkey see, monkey do) but these are disputed.
In any case, cephalopods seem to be pretty smart. Cephalopod intelligence is an interesting topic because cephalopods are invertebrates, lacking a spinal cord. They have large, complex neural systems with fairly large brains. Which are wrapped around their esophaguses. Seriously.
See? By the way, I found that here. Because citations are important. You’re welcome.
Cephalopods have these giant nerve cells with axons about 1 mm thick that are responsible for their extremely rapid escape response. Stimulation of these neurons results in contraction of a series of muscles causing water to be forced out of the animal, moving it backwards.
Cephalopods also have chromophores, which are basically pigment sacs under the skin that allow their skin to change color. (So cool!) The chromophores are strongly linked to the animal’s visual input, since the color-changing thing is used for protective camoflage and signaling when predators, prey, mates, or rivals are around. So cephalopods also have this complicated neural system for processing all visual input and controlling the chromophores.
Then there’s the whole learning and memory thing, which was what I was going to talk about originally… (Some days, the ADD wins, okay?) The physical stuff behind the learning and memory is very complicated and not very well understood. Simpler systems are easier to research, and these are not simple systems. From what has been found so far, however, it is apparent that cephalopods have two distinct systems for visual learning and memory and for tactile learning and memory…and that’s about all I’ve got for you.
This is so not a satisfying entry! I wanted to address the question “why are cephalopods so smart?” And I kind of did, but I couldn’t answer it beyond “they have big, complex neural systems.” This is partially because we simply do not understand how brains work in very much detail and partially because it’s a really complicated topic. I mean, look! There’s a 560 page textbook just on coleoid cephalopod neurobiology. Oh well. Points for trying?
Finn, J. K.; Tregenza, T.; Norman, M. D., Defensive tool use in a coconut-carrying octopus. Current Biology 2009, 19 (23), R1069-R1070.
Williamson, R.; Chrachri, A., Cephalopod neural networks. Neurosignals 2004, 13, 87-98.