Game
Heat Sense
See the dusk the way a pit viper does. Find warm prey among cool and sun-warmed stones, then strike before it slips away.
Based on published research · pending expert review
Level 1 of 5Open sand
Found0 of 1
Score0
Aim with the arrow keys, mouse or a finger. On a touchscreen, tap to strike, or touch and hold the scene for heat sense. F toggles full screen.
Find warm prey before it slips away
You are a pit viper at dusk. Your eyes see camouflage; your heat sense sees warmth. Use both.
Hold Space or the heat sense button to see warmth. Touch and hold works too.
Aim with the arrow keys, the mouse or your finger.
Strike with Enter, a click or a tap. Stones warmed by the sun cool down; animals stay warm.
Results
Level by level
What the pit can and can’t do
Warm ground and stones can create false patterns, so a snake cannot simply strike the warmest spot. Free-ranging sidewinder rattlesnakes responded to lizards more often when the lizard's temperature contrasted strongly with its background.3,5
With no visual cues, western diamondback rattlesnakes reacted to a warm, mouse-sized target up to 1 m away. Rattlesnakes use this sense to find warm prey at night, when there is little to see.2,7
Meet the snakes
- Western diamondback rattlesnake
A pit viper. It has a heat-sensing pit on each side of its face.1,2
- Russell's viper
A true viper with no pit between the nostril and the eye.8
The science
How a pit viper senses heat
A pit between the eye and the nostril
Pit vipers, such as rattlesnakes, have a heat-sensing pit organ on each side of the face, between the eye and the nostril. Infrared radiation from warm prey heats a thin membrane inside it, so the pit senses heat rather than light.1
Hunting without light
With no visual cues, western diamondback rattlesnakes reacted to a warm, mouse-sized target up to 1 m away. Rattlesnakes use this sense to find warm prey at night, when there is little to see.2,7
A blurry, faint image
The image the pit forms is poorly focused and very low in contrast. To explain what snakes can do, its sensors probably respond to temperature differences of 0.001 °C or less.3
Heat and sight together
Signals from the pits and the eyes meet in a part of the brain called the optic tectum. Some nerve cells there respond only when both senses are stimulated at once.4
It senses contrast, not life
Warm ground and stones can create false patterns, so a snake cannot simply strike the warmest spot. Free-ranging sidewinder rattlesnakes responded to lizards more often when the lizard's temperature contrasted strongly with its background.3,5
Not every viper has pits
Russell's viper is a true viper and has no sensory pit between the nostril and the eye. In tests of 12 pit viper species and one true viper, only the pit vipers could use thermal radiation to guide where they moved to warm up or cool down.8,6
References
- 1
Gracheva, E.O., Ingolia, N.T., Kelly, Y.M., Cordero-Morales, J.F., Hollopeter, G., Chesler, A.T., Sánchez, E.E., Perez, J.C., Weissman, J.S. & Julius, D. (2010). Molecular basis of infrared detection by snakes. Nature 464: 1006–1011. pmc.ncbi.nlm.nih.gov
- 2
Ebert, J. & Westhoff, G. (2006). Behavioural examination of the infrared sensitivity of rattlesnakes (Crotalus atrox). Journal of Comparative Physiology A 192: 941–947. pubmed.ncbi.nlm.nih.gov
- 3
Bakken, G.S. & Krochmal, A.R. (2007). The imaging properties and sensitivity of the facial pits of pitvipers as determined by optical and heat-transfer analysis. Journal of Experimental Biology 210: 2801–2810. pubmed.ncbi.nlm.nih.gov
- 4
Newman, E.A. & Hartline, P.H. (1981). Integration of visual and infrared information in bimodal neurons in the rattlesnake optic tectum. Science 213: 789–791. pubmed.ncbi.nlm.nih.gov
- 5
Schraft, H.A., Goodman, C. & Clark, R.W. (2018). Do free-ranging rattlesnakes use thermal cues to evaluate prey? Journal of Comparative Physiology A 204: 295–303. pubmed.ncbi.nlm.nih.gov
- 6
Krochmal, A.R., Bakken, G.S. & LaDuc, T.J. (2004). Heat in evolution's kitchen: evolutionary perspectives on the functions and origin of the facial pit of pitvipers (Viperidae: Crotalinae). Journal of Experimental Biology 207: 4231–4238. pubmed.ncbi.nlm.nih.gov
- 7
Schraft, H.A., Bakken, G.S. & Clark, R.W. (2019). Infrared-sensing snakes select ambush orientation based on thermal backgrounds. Scientific Reports 9: 3950. pmc.ncbi.nlm.nih.gov
- 8
Uetz, P. et al. (eds.) (2026). Daboia russelii (Shaw & Nodder, 1797). The Reptile Database. reptile-database.reptarium.cz
The game simplifies what the pit organ does: the heat view is an illustration, not a measured image. The facts above are based on published research and are waiting for review by a specialist.