Nestled between the mountain ranges in the south-western Earth Kingdom, near the large town of Gaoling lies the Foggy Swamp - also known as the ‘Foggy Bottom’ or simply ‘The Swamp’. It is a largely freshwater wetland with densely populated flora and fauna.
Even with seasonal variations, the weather here is mild all year round which allows it to support a diverse ecosystem like no other. The lush grasses, bushy shrubs and towering trees allow a plethora of unique animal species to flourish - insects, worms, amphibians, reptiles and birds found here in abundance have intrigued zoologists and botanists for over a century.
One of the more peculiar species found here is a species of bipedal lizard - Toph beifongensis. These lizards can be found on small trees as well as land. They prey on mealworms, earthworms, silkworms and other small critters.
On first glance, they look like normal lizards you would find anywhere else in the world. However, what makes this species distinct from all others is the presence of a bundle of special neurons - nerve cells. These are mechanosensitive neurons - they are sensitive to mechanical stimuli like pressure and vibrations and send action potentials - messages encoded as electrical impulses - in response to them. These neurons are not that special in and of themselves - what makes them special is their location. Toph beifongenesis have a bundle of mechanosensitive neurons in their hind feet.
The function and inner workings of these strange neurons eluded scientists for decades. However, a relatively simple experiment unraveled their secrets. Let’s rewind the clock to this experiment and see how this happened.