It doesn't make sense to have a scale of consciousness. The argument that consciousness is a manifestation of a complex brain is rather weak. Either an organism knows about self, and therefore tries to preserve self. Or it doesn't. I don't see how an in between exists.
If you take the view that consciousness somehow arises from the brain and neural connections (which is intuitively plausible, but I personally am skeptical), it stands to reason that other species with complex brains are conscious as well. Perhaps "less conscious" (if that means anything) in proportion to how much less complex their brains are.