Embora eu não consiga encontrar nenhuma indicação de como eles fazem isso, eles definitivamente excretam o lixo.
No livro 14, os animorphs descobrem um toalete Andalite.
<So? So what is it?> Marco demanded.
<lt's a disposable module of a type used in the old days on the first generation of Andalite Dome ships. When the modules were used up, they were jettisoned into space. They were supposed to be aimed toward a star, so they'd be burned up without a trace. This one must have drifted through space, eventually being caught by Earth's gravity.>
<So it's a space engine?>
<lt's a weapon?>
<No, of course not. It's . . . well, this is a bit embarrassing. It's an Andalite Dome ship's modular waste disposal system.>
For about a full minute, no one said anything. Then Marco spoke.
<You're telling me the Most Secret Place On Earth, the fabled Zone Ninety-one, the Holy Grail of conspiracy nuts, is hiding the secret of an Andalite toilet?><Only a very primitive model,> Ax said condescendingly. <Since those days there have been huge technological improvements.>
Animorphs #14: The Unknown - Chapter 20
O vaso sanitário em si não é bem descrito e não é possível determinar muitos detalhes sobre seus métodos de operação.
Até onde eu sei, o mais próximo que os livros chegam de discutir o sistema excretor de Andalite está no livro 49.It was about eight feet across. The shape was like a cube with the corners rounded off. The entire surface was covered with tubing and painted symbols. At one end was an opening, large enough for a person to walk inside. I could just barely get a glimpse of the inside. It was smooth, a lovely green in color, with soft lighting. There was some sort of instrumentation on one wall.
Animorphs #14: The Unknown - Chapter 19
"Amazing." Cassie's mom reached out and ran her hand across the blue fur on Ax's rump.
"Mom!" Cassie snatched her mother's hand away. "Would you play with Jake's butt?"
"Of course not!"
"Then quit playing with Ax's!"
Animorphs #49: The Diversion - Chapter 15