Nakula is the fifth of the sixteen Arahants. He was a brave warrior before he became a monk. When he was a monk," Buddha asked him to give up his rude, savage character and made him practice “sitting in calmness”. But while he sat calm he still displayed the spirit of a warrior. Eventually, Nakula understood the Dharma through Zen meditation, and obtained the position of Arhat. Hence, he is called “Arhat sitting in calmness”.
Karika is the seventh of the sixteen Arahants. He was an elephant trainer before he became a follower of Buddha. Elephant in Sanskrit is Kari, Karika means rider of elephants. Elephants are very strong, but also have great endurance, which is a symbol of Dharma. This is why Karika is called the “Elephant riding Arhat”.