A pack carrier is a person or animal that carries goods or supplies on their back. The term can be used to refer to four different animals: LLAMA, ASS, BURRO, and MULE. A LLAMA is a domesticated South American mammal with long fur and a long neck. An ASS is a domesticated member of the horse family, typically smaller than a horse. A BURRO is a small donkey, often used as a pack animal in the southwestern United States. Finally, a MULE is a hybrid of a donkey and a horse, bred for strength and endurance. All four animals are used as pack carriers, carrying goods and supplies on their backs.