A semi advanced race the was counquered by the Yeerk empire. The visible organs are decoys.
Orff can see in the dark, as they come from a world were the night is long, 24 hours out of a 30 hour day. So they are not used to being in day light for a period lasting longer then six hours. They can handle it how ever. A larger problem come sin when UV radiation is involved, their systems are not designed to handle it as well as say, a Human or Andalite.