How Does a Duck Know?

How does a duck know what direction south is?
And how to tell his wife from all the other ducks?
You can cut a chicken's head off
And it will keep on running and twitching

When everything seems planned out
When everything seems nicely planned out
Well the human race will come and smack your face

How come all my body parts so nicely fit together?
All my organs doing their jobs, no help from me!
A person pulls a spider's leg out
To watch it keep on moving and twitching

Satan lives here: on grain and earth, rain and air

How come I just smoke and smoke and smoke
And curse every butt I spit out?
All night long I grind my teeth and I wake up when I cough
You can put me in an iron lung
And I will keep on breathing and twitching