While possessing a large brain does not necessarily mean that a creature is of high intelligence,
the cetacean's lifestyle revolves around various  techniques in hunting and foraging for food
 and avoiding predation in complex three dimensional spaces, implying that their increased brain size
is in part related to their various navigation and commuication skills. The  Cetacean brain must be able
 to learn, maintain and process click-based echolocation and navigate through a myriad of complex
foraging strategies. Other intellectual necessities compiled in the structure of Cetacean brains
 are the forming and recollection of complex social relationships.  Cetaceans learn tricks well in
captivity showing that they have the ability to learn from their own and other species.
 The increased brain size spoken of in the phylogeny section speaks to the development of a capacity
 for advanced learning.