Garatrons are a sapient species that have become an unwilling host species of the parasitic Yeerks.
Garatrons are centaur like aliens with frail arms, two eyes, a bicyclist helmet like head and a long tail. They eerily resemble the Andalites, but the two species are not related to each other, rather they are an example of convergent evolution. Garatrons do not have an axe like blade on their tail, nor do they have two stalk eyes one their head like Andalites. Garatrons are however are much faster then an Andalite ever could be, and can even run on water. Additionally, while they lack a blade at the end of their tail, they are able to use their tail as wimp, which they swing at foes at incredible speeds, causing great harm to their adversaries.
Garatrons have no visible mouth, at its assumed they have mouths located under their hooves, much like their Andalite counterparts. Because of this, Garatrons speak telepathically like Andalites, though their telepathic speech is extreme fast, almost to the point of being non-coherent.