Game
Scent Trail
A snake smells with its tongue, from two points at once. Flick, feel which side is stronger, and follow the trail.
Based on published research · pending expert review
Each tip of a snake's forked tongue delivers scent to its own vomeronasal organ, so the brain can tell at once which side smells stronger.2
Meet the Indian rat snakeIn 1994 Kurt Schwenk used film and photographs to show that snakes spread their tongue tips far apart just as they touch the ground, sampling two points at once.1,2
Meet the Indian rat snakeIndian rat snakes are active by day, and on farms they sometimes enter houses in search of rodents.5
Meet the Indian rat snakeFlicked in the air, a snake's tongue makes two pairs of tiny swirling vortices that act like fans, pulling odours in from each side towards each tip.2
Meet the Indian rat snakeForked tongues have evolved at least twice among lizards and snakes, and across larger groups they always go with a wide-searching way of finding food.1
Meet the Indian rat snakeWestern diamondbacks tell a bitten mouse from an unbitten one by proteins from their own venom, called disintegrins, left in the bitten mouse.4
Meet the Western diamondback rattlesnakeTrail 1 of 6First trail
Trail 1 of 6
First trail
A field mouse crossed the bund at dawn. Flick your tongue, feel which side is stronger, and follow it to where it hid.
- Flick: Space, the Flick button, or tap the head.
- The arcs at the two tips grow with the scent. Compare them.
- Turn towards the stronger side and find the hiding place.
Paused
The trail will wait. Game time has stopped.
Found it
- Time
- 0:00
- Flicks
- 0
- Score
- 0
Every trail followed
Your best scores add up to 0 out of 6000.
Whether snakes really steer by comparing the two tips is still being tested. One experiment with rattlesnakes found they trailed just as well with one side of the sense cut off.3
Meet the Indian rat snakeMeet the Western diamondback rattlesnake
Flick to smell
Keys: ← → turn, ↑ ↓ faster or slower, Space flick, P pause. Touch: drag on the board to steer, tap the head or Flick to smell. A gamepad works too.
Trails
Smelling in stereo
When a snake flicks its tongue, the tips pick up scent particles and carry them to the vomeronasal (Jacobson's) organs, which open into the roof of the mouth.2
On the ground, snakes spread the two tips far apart, so they sample two points at once. Each tip delivers to its own organ, so the brain can tell at once which side smells stronger.1,2
In 1994 Kurt Schwenk proposed that this makes the forked tongue an edge detector for following the scent trails of prey and of other snakes. The idea is still debated: in a 2008 test, rattlesnakes with the nerve cut on one side still followed prey trails normally.1,3
Vipers strike, let go, and then follow the bitten animal, which may wander several metres or more. They have to tell its trail apart from the trails of animals they did not bite.4
In the game the scent field is simplified: trail width, fading, wind and the strength words are game rules, not measurements.
References
- 1
Schwenk, K. (1994). Why snakes have forked tongues. Science 263(5153): 1573–1577. doi.org
- 2
Schwenk, K. (2021). Smelling in stereo: the real reason snakes have flicking, forked tongues. UConn Today (first published in The Conversation). today.uconn.edu
- 3
Parker, M.R., Young, B.A. & Kardong, K.V. (2008). The forked tongue and edge detection in snakes (Crotalus oreganus): an experimental test. Journal of Comparative Psychology 122(1): 35–40. doi.org
- 4
Saviola, A.J., Chiszar, D., Busch, C. & Mackessy, S.P. (2013). Molecular basis for prey relocation in viperid snakes. BMC Biology 11: 20. pmc.ncbi.nlm.nih.gov
- 5
School of Biological Sciences, The University of Hong Kong. Ptyas mucosus (Linnaeus, 1758), Common Rat Snake. Hong Kong Reptiles. biosch.hku.hk