sit (st)
v. sat (st), sit·ting, sits
v.intr.
1. To rest with the torso vertical and the body supported on the buttocks.
2.
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.
7.
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.