Yukkuri was in fact a secret-agent from the Sigma Draconis who had defected, and hid inside that Mother Yukkuri. It was eventually consumed by the Yukkuri and by the wonder of Yukkuri genetics, it was turned into a yukkuri. Normally, this would confer to it a great advantage, but just in case this sort of thing happens it was implanted with a bomb written into its DNA that detonated with the words, "take it easy." what you see, with those lines, is the bomb activating.
The ko is infested by Thetans, and after birth, has had her mandatory period of silence compromised by her mother and father, thus implanting an engram. Unlike humans, yukkuri babies can cognitize from the moment of birth, so the ko - recognizing this - is objecting to a situation she can't get handled.