Written by Lila Cart; Illustration by Zach Herman

Infrared sensing snakes include boas (Boidae), pythons (Pythonidae), and pit vipers (subfamily Crotalinae of Viperidae). Infrared is a temperature based sense that connects to the visual system. Infrared is sensed through a structure called the pit organ. Infrared sensors travel to the brain through a special processing center called the LTTD (lateral descending tract and nucleus of the trigeminal nerve).

Infrared neurons have a background discharge, meaning they are continuously firing, and change their firing pattern in response to stimuli of different temperatures. Infrared and visual field information meet in the optic tectum of the contralateral (opposite) side of the brain. The means that information from the right visual and infrared field is sent to the left side of the brain for processing.


  • Goris, R. C. (2011). Infrared Organs of Snakes: An Integral Part of Vision. Journal of Herpetology,45(1), 2-14. doi:10.1670/10-238.1