Gatz wrote:Yumi wrote:genjutsu can't be used on or by most animals.
What? Ma and Pa use a singing Genjutsu! Also, Sasuke locks Manda in a Genjutsu. I'd love to have my pet be able to inflict terrible Genjutsu on my opponents.
Genjutsu targets the brain of the enemy and, strictly speaking, only mammalian species typically have the area of the brain that is primarily affected.
This has also been mentioned canon in the anime, explaining why Shino (with bugs that don't have the required brain structure to be the target of Genjutsu and, thus, are immune) have an advantage in seeing through it.