The term 'iguana' refers to a species of LIZARD found in tropical climates. It is closely related to the Chuckwalla, which is a large LIZARD found in the deserts of the southwestern United States and northern Mexico. Both the iguana and the chuckwalla are members of the same family of lizards, known as Iguanidae. They both have long tails, scaly skin, and sharp claws. The iguana is typically green in color, while the chuckwalla is usually brown or gray.