It's pretty similar to the bird as far as function goes but these are only found in the cavern environments. They don't move until provoked, at which point they wake up and probably try to bite you or something. Well, they would if they had a mouth.
Normally they hang motionless from the ceiling:
When you get close enough the code transitions the sprite into its flying animation.
Still working within the 8 frame limit, but I wanted the bat to have a slightly more streamlined motion as opposed to the bird which is more erratic. If they end up moving anything like Keese from the Legend of Zelda these things will be a pain to deal with.