Can creatures spawn in caves?

Looking for creatures to get the bonus units for finding them all is quite tedious. Finding them on land and in water is difficult enough already.

I was wondering, has anyone seen any in a cave at all? Do they spawn in caves? I've yet to see any in them, but because of this, I tend to stay away from the caves and focus more on finding creatures elsewhere. I just don't want to be wasting anymore time looking on land if say the last creature I need is tucked away in a cave.

Yes. Creatures are able to spawn in caves, sometimes exclusively. Some only come out at night, as well. It varies from planet to planet.

Certain species may only spawn at night or in particular environments, such as caves, low (or high) altitudes, or in extreme weather conditions.

Source