Well, I did learn that if you enter "dog" or "bird" into the "Search" field, the Organizer will retrieve dog or bird photos. It works the same way to recall most species of animal or type of object you have in your collection. I tried "rabbit", "elephant" "car" and "water" as examples. I'd say it was about 90% accurate. I never labeled those photos with these names, either.
Interestingly, if I search the name Pomeranian, it will not select anything. But if I search the name Chihuahua, all the dogs come up of all breeds.
So for folks who use the app "Search Everything" instead of the Organizer, it looks like this is one feature they don't have.