Thought-speak is the way Andalites communicate since they have no mouths. It is a language that almost all species can understand. It is not quite telepathy, as beings using thought-speak communicate through universal mind symbols rather than actual thoughts; however, it is like telepathy in that there is no sound being transmitted or received. There are two different types of thought-speak: open and closed. Open thought-speak is where you broadcast what you're thinking to everyone, while closed thought-speak is where you communicate to one person or a selected few. In the Animorphs books, thought speak is represented using the characters < and >, to differentiate it from normal speech, which is represented using quotations.