Board Thread:Naruto Discussions/@comment-25228549-20140821104935/@comment-1512913-20140824175645

@Ulti, if you bothered to read above, the voice actors have no relevance. Mythical Tanuki are male only to my knowledge, with Gaara's gourd referencing Shukaku's scrotum. Son Goku refers to himself as King and handsome, that's male. Oxes/bulls are male only, so Gyuki is male. Only male beetles have horns, so Chomei is male.

That's sex dimorphism there.