Comment by HarHarVeryFunny

Because:

1) It's a poorly defined word that means different things to different people

2) The word "mechanism" perfectly describes what it is

At the end of the day it's just using the detection of food, to switch from "tumble" (try a random direction to find food) to "run" (assume we're near, or in, a patch of food, and move forward to consume more).