I just recently own an iguana and find it useful the tips I read at , Iguana Teeth to know whether your iguana is preparing to bite you.

1. Bringing its arms forward and lifting itself up
2. Deploying his dewlap, the flap of skin under its chin
3. Inflating itself with air in order to make it look bigger and more threatening
4. Flashing of it eyes pupils, meaning constricting and dilating
5. And Head bobbing vigorously

Anyone experience being bitten by Iguana?