What is the symbolism of the Iguana in Night of the Iguana?

Chicken-of-the-Jungle, a land-locked cousin to the Blue-fin tuna, but tastier, that -- wait for it -- really tastes like chicken. Like chicken on a stick, or chicken barely alive, constrained to a pole with a sharp rope, as sharp as the cross hanging from a defrocked sexual predator. Do iguanas live at Penn State?