Grades 3–5 · Organisms
Why does a snake keep flicking its forked tongue?
A snake's flicking tongue brings in chemical samples from its surroundings. Traces from other animals or nearby material gather on the extended tongue, whose two tips sample separated positions. Repeated flicks collect fresh material as the snake explores.
The tongue returns into the mouth and delivers collected material to a specialized sensing system associated with its roof. This is often called the Jacobson's organ, or vomeronasal organ. The exposed tongue gathers the sample; sensory tissue inside responds to its chemicals.
Nerve messages then carry information toward the brain. A snake investigating an animal's trail can receive information that is not visible in the scene. The traces are actual material left in the surroundings, rather than tiny drawings or arrows that the snake reads.
Chemical traces lie outside the mouth, while sample returns inside points toward the sensing system in mouth. The tongue gathers material; the internal sensory tissue detects its chemicals.
In the diagramThe tongue collects; sensory tissue detectssample returns insidechemical tracessensing system in mouthSampling is one part of the snake’s sensory equipment.
Each return brings collected material to sensory tissue inside the mouth, followed by nerve messages for the brain to interpret. The fork alone does not explain every turn: snakes also use nostrils, eyes and other senses. Sampling, detecting and interpreting are connected but different jobs.
About this explanation
Starting knowledge: Understand that tiny chemical traces can carry information about an animal’s surroundings.
Sources
- San Diego Zoo Wildlife Alliance — Rattlesnake: Habitat and Diet
- Science — Why snakes have forked tongues
- Journal of Comparative Psychology — The forked tongue and edge detection in snakes (Crotalus oreganus): an experimental test