Specialised infrared receptors, the heat-sensitive receptors or pit organs, occur in the labial pits of [[Boidae|boids]] and [[Pythoninae|pythons]], and the heat pits of [[Pit viper|pit vipers]]. | Specialised infrared receptors, the heat-sensitive receptors or pit organs, occur in the labial pits of [[Boidae|boids]] and [[Pythoninae|pythons]], and the heat pits of [[Pit viper|pit vipers]]. |