v. sat (st), sit·ting, sits
1. To rest with the torso vertical and the body supported on the buttocks.
a. To rest with the hindquarters lowered onto a supporting surface. Used of animals.
b. To perch. Used of birds.
3. To cover eggs for hatching; brood.
6. To pose for an artist or photographer.
a. To occupy a seat as a member of a body of officials: sit in Congress.
Of the above, I'd say 3 and 6 apply. And depending on your definition of snake, then 7a applies as well.