Llamas are relatives of the camel. They can be stubborn, refusing to move if there is too much weight that they are supposed to carry. I guess that just means that llamas are very smart, and don't want to tire themselves out with too big of a load.

http://www.asewinghabit.co.uk/userimages/llama.jpg

http://www.llowc.com/Photos/puck%20copy.jpg

http://pbs.twimg.com/media/BAmL_hQCIAAKnxm.jpg:thumb

http://4.bp.blogspot.com/_W90V87w3sr8/TOyjld32uwI/AAAAAAAAAQo/CMU8I19kfpA/s1600/llama.jpg