I haven't seen any snakes or spiders around the Vistana, but I'm sure they're there.....they would just prefer to hide out. The foliage and gardens are so lush and beautiful that its certainly where I would choose to make my home if I were a slithery or creepy-crawly creature

. If I happened, by chance, to see either of those animals I would probably steer clear, just to be safe. I am certain they will be equally happy to avoid you too!
Alligators....haven't seen those at the resort either (though they are prevalent in lakes and swampy areas). Gatorland brings their travelling show to the resort once a week, though, so if you WANT to see a gator, it will be convenient to do so.
If, by some fluke, you DO see a gator waltz out from one of the little ponds and lakes at the resort (I know small ones have been spotted at Disney resorts from time to time), I would beat a path to the villa and report it to management. I am sure they have something in place to handle such situations, as gator are protected in the state of Florida. They would capture and relocate him to a much more suitable habitat, away from tourists.
One thing you WILL see at the resort are zillions of these guys:
They're harmless little lizards that are lightning fast. They like to crawl up walls and zip past your toes as you walk down the sidewalks. You have nothing to fear from them, though if one gets inside your villa it may be next to impossible to catch it. So just be sure there's none on the door or door fram when you enter and exit your villa and you'll be fine

.
The only "wild animals" we fear are the folks who choose to text and drive

. They are far more dangerous than any creature you might find at the resort.
You know what I am dying to see some day? A real live armadillo. I keep peeking around the bushes to see if I can spot one, but so far....no luck. The Vistana staff have said they're there, but none have come out to say hello just yet.