The Buddhist wheel of life depicts the realms symbolically, and they represent the various conditions of the mind and its emotions. "In addition to being a valuable guide to Buddhist thought, it is also one of the most comprehensive pieces of psychological symbolism that I am aware of." ---awjuliani on medium
In the Buddhist wheel of life, the frightening creature holding the wheel is Yama, who represents impermanence. In the Vedas, he became the lord of death. In Buddhism, Yama was the dharma protector. I think his depiction here is symbolic in that death is the only unchanging fact of life.
"The figure of death holds up the mirror so that we can see our own reflections. It’s all just an image of our lives, our minds. Though it seems real while it’s happening, these ups and downs are just a mirage—" ---http://buddhismnow.com