"Oni ga aru?" or "Oni ga iru?"
More generally, I'm asking how the Japanese distinguish between living things (iru) and non-living things. The following is a list of nouns I'm unsure how the Japanese categorize (whether used with 'iru" or "aru"):

- Demons
- Ghosts
- Vampires
- Zombies
- Plants
- Feet
- Hands
- Viruses
- The universe

Anyone who can enlighten me on this would be greatly appreciated. Thanks!

Question

"Oni ga aru?" or "Oni ga iru?"
More generally, I'm asking how the Japanese distinguish between living things (iru) and non-living things. The following is a list of nouns I'm unsure how the Japanese categorize (whether used with 'iru" or "aru"):

- Demons
- Ghosts
- Vampires
- Zombies
- Plants
- Feet
- Hands
- Viruses
- The universe

Anyone who can enlighten me on this would be greatly appreciated. Thanks!

Answer

I would write how we say in general. (In some poet or something, it may be changed by authors or speakers.) 
- Demons いる
- Ghosts いる
- Vampires いる
- Zombies いる
- Plants ある
- Feet ある
- Hands ある
- Viruses いる and ある
- The universe ある

I hope this helps you.

Answer

this sounds like a strange method, but what i like to do when i am unsure about which word to use, i do a quick check in my google search bar, and usually the commonly asked quesiton/used phrase will appear.
here is what i mean:

http://imgur.com/OClU88Y
http://imgur.com/a3tthBV

that method helps me a lot when i feel like i need to make a quick judgment.
of course it's always best to refer to a native speaker of that language.

hope it helps, though!