pierna/pata
It seems like "pierna" is for people and "pata" is for animals. Is this true?
5 Answers
Exactly.
Pata is also used for the leg of a table.
Yes, and like Mariana said, furniture also has patas.
Patas is also used in some phrases, like patas arriba, meaning upside down or topsy turvy.
Note that pata normally includes the leg and foot of an animal, but pierna does not include the foot of people.
And then there is malapata = someone who is clumsy or just a chav a bumpkin
I did a cursory search on here but probably could've looked longer... wondering if there is a list out there somewhere with equivalent animal body parts that should be used accordingly.
Some terms are used for animals but not for humans (unless used tongue-in-cheek). For example, el hocico and el pescuezo are often used to refer to the nose (snout, to include the mouth) and neck of animals, respectively. Pata and pie can be added to this list, but I am curious if there are others... besides words like trompa or cuerno (obviously!) 
