I found it, thanks!
Does anyone else think this could've been better written?
Marco seems to shrug it off - and yeah, he's used to Taxxons by now - but there's a big difference between eating someone else and eating yourself.
Maybe it was downplayed so it would sneak by the editor? It was the first ghostwritten book, after all...
I think that a lot of things are downplayed, just as a general rule. It is a YA book series, after all. You know how the narrators of any particular book occasionally mention all the nightmares they have of previous battles or previous missions? I think that's downplaying right there. In reality, most (if not all) members of the animorphs should be post-traumatic stress disorder trainwrecks, who twitch into borderline combat-morph rage every time an elderly woman takes them by surprise at the corner of a supermarket aisle, their ability to empathize with living creatures eroded to the point of sociapathy by the numberless times they have had to murder other living beings with nothing but their own teeth and claws and feel the life-blood of their victims pulsing warm and wet over their own tongues, who are plagued each and every night by nightmares of the endless cycle of bloodshed and violence that consumes their lives.
...But, somehow the Animorphs maintain their sense of morality and are able to remain grounded in reality. Quite remarkable, really. Either young kids just deal with this inter-species warfare stuff better, or the Ellimist had a hand in "coincidentally" assembling a group of children who just happened to be very, very psychologically suited to dealing with this sort of trauma.