Homeworld: Yeerk homeworld
Home system: Kandrona
Home galaxy: Milky Way
Current population: Billions
Primary language: Sonar, Galard.
Fur/skin tone: Slimy green/brown
Affiliation: Yeerk empire
Current status: Galactic power
The Yeerks used to be leech like predators. For a comprehensive read of early Yeerk history, click here. After gaining access to Andalite technology, they became a scourge on the MW. They have attacked and conquered many races, including the Gedds, Nahara, Mak, Hork-Bajir, Ssstram, Orff, Xandarans and members of other races, like the Onganchic and one Andalite. They have an ally race, the Taxxons.
The Yeerks are a parasitic species. They attack and infest or kill other species. Without hosts, they are blind, deaf, and slow slug like creatures. They leave their host and feed off of Kandrona rays every three Earth days, the rays came from their home sun, but they now have the technology to generate Kandrona rays. This has allowed them to expand through out the Milky Way galaxy.