[bduerst]

Octopodes have their own evolutionary barriers though, irrespective of intelligence:

- They only typically live 4 years and the act of reproducing kills them

- They live in coastal ocean biomes, which have high selective pressures

In order for intelligence to flourish, a form of communication is needed and the method to transfer knowledge from one generation to the next. An octopus is a solitary organism, unlike mammals which are tribal. It does not live long enough to develop social skills or to transfer knowledge to their offspring, so there isn't any accumulation of information for their species to build cities or technologies. Each individual is forced to self educate and re learn survival.

Your criteria for intelligence is more criteria for safe habitat than intelligence. Just because they don't live long enough to learn language or write books doesn't mean they are not intelligent.