A cold iguana loses control before it freezes
Iguanas are ectotherms: their bodies rely on outside heat rather than generating enough warmth internally to stay at a steady temperature. On a chilly Florida morning, an iguana perched in a tree cools along with the air around it. As its body temperature falls, the chemical reactions that power its muscles slow down. Nerve signals and muscle contractions become less effective, making it harder to keep its toes curled tightly around a branch.
The lizard does not have to be frozen solid for this to happen. “Frozen” in this setting describes cold-induced immobility, not necessarily ice forming inside the animal. Once its grip gives way, it drops under its own weight.
Why warming can change the outcome
The same dependence on environmental heat that causes the problem can allow recovery. If sunlight or warmer air raises the iguana’s body temperature, its nerves and muscles can begin working better again. That does not mean every fallen iguana will recover; the outcome depends on how cold and how long it has been exposed, as well as its condition.
The striking sight is therefore a moment in a temperature-driven process: an animal that seemed abruptly lifeless may regain movement as its body warms. A fall from a tree is not, by itself, proof that the iguana is dead.
