Why should intelligence _other_ than motor-planning be tied to the degrees of freedom of their movement? - snakes have a high number of degrees of freedom but

Why should intelligence _other_ than motor-planning be tied to the degrees of freedom of their movement? - snakes have a high number of degrees of freedom but aren't especially bright - squid have 2 more limbs than octopuses and aren't as smart I think the shallow-water vs deep-water thing mentioned in the article is important; reef and similar environments give a lot more opportunities for smart camouflage, complex navigation, tool-use opportunities etc than the open ocean.