tonmo said:
certainly the octopuses in this forum have displayed some very clever and what would seem to be "thoughtful" behavior.
This is purely my opinion:
I think it is worth remembering that octopuses that tend to be sold as pets come from shallow water habitats, often coral reefs, where in their natural habitat they are surrounded by visual and other sensual stimuli. They need finely tuned senses to detect the presence of predators, their own prey items and their own shelters. In other words, the habitat these animals live in is forever changing and would dictate an elevated awareness of their surroundings that is essential to their survival.
A cephalopod living in the dark mid water columns or the abyssal depths would live in a much more stagnant and repetitive environment lacking diversity. In my opinion, this lack of stimulus would lead to a creature that is so much less aware of environmental stimuli (excluding the environment of its own niche) than its shallow water cousins. Whether or not this means that it is less 'intelligent' is a matter of choice and depends on how one wishes to define the term.
Architeuthis, for example, is probably happy to hang there at, say, 600m depth at an angle waiting for prey to drift past. It has poor musculature implying that it does not need to chase after its prey or require the intelligence to know how to do so. With a net spread with its arms, it barely needs to 'think' as prey will drift its way towards it. The fact that the creature exists is enough to prove that.
I think that anyone was fortunate enough to own a deepwater
Vulcanoctopus or
Grimpoteuthis in a tank at home would be sorely disappointed at the lack of 'intelligence' shown; 'intelligence' could be read as an awareness of the environment. I don't think that the fact that that pet octopi display intelligent behavioral traits should be indicative of coleoids as a whole, indeed, I think that it is purely a response to the environment that the particular species originates from.
I would also wonder how much 'emotive' behaviour exhibited in octopi is an anthropomorphic projection what we wish to see. After all, we all know that when a cat rubs itself against your leg it is not genuinely showing affection, but merely rubbing its scent onto you to display territorial possession. Yet it's hard to recognise this, even if one knows it.
But what do I know? I've never kept a pet goldfish, let alone a cephalopod!