Talk Nerdy To Me: “Thigmotaxis”

A blog series that teaches you complex science words which are sure to impress at the dinner table. Whether you are on a date, trying to impress your boss, or just trying to prove to your mom and dad that you have been listening in science class, this blog series is sure to come in handy!

"Thigmotaxis" Definition: The orientation of an organism in response to a touch stimulus.

Nearly all living things respond to physical touch in some way. But perhaps one of the more dramatic examples of thigmotaxis comes from carnivorous plants such as the sundew plant. As its potential meal creeps onto the sundew plant’s sticky tentacles and becomes stuck, the plant responds to the tasty intruder’s creeping by bending its tentacle inward, ensnaring and eventually devouring the intruder. The sundew plant, and other organisms with a similar tactic, exhibit what is known as “positive thigmotactic response,” or moving towards the object in response to the physical touch. The sundew’s meal on the other hand likely exhibited “negative thigmotactic response,” or (attempting to) move away from the object (the sundew) in response to the physical touch of the sticky tentacles.

Round-leaved sundew on heathland, New Forest by Jim Champion is licensed under CC-BY-SA 2.0

Humans are known to exhibit both positive and negative thigmotaxis. But humans are more complicated, because their response to physical touch is dependent upon their feelings and emotions, or responses generated from the brain. For example, in response to the physical touch of a loved one’s embrace, humans will likely exhibit positive thigmotaxis and thus move towards the stimulus. On the other hand, in response to the physical touch of a stranger, especially someone that is not trusted, negative thigmotaxis will be expressed as the human will move away from the stimulus. Fear can also dictate the type of thigmotactic response generated by humans. Studies show that humans, when under stress and in response to fear, will stay away from open spaces, and the physical touch of other people, and move towards walls in search for an exit. Interestingly, this same response is expressed in the lowly cockroach whenever it finds itself out in the open and under stress, it will quickly move towards, and run around, the nearest wall. The next time you see a cockroach and try to squish it, keep in mind that you are more similar to the cockroach than you think!

[Click “go” in the image below to learn some “Thigmotaxis” phrases to use at dinner time!]

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