Any fashion aficionado knows the little bumps dotting crocodiles' and alligators' leather can help you tell the difference between the species' skins. But researchers have discovered that the domes on the skin's surface are more sensitive to the touch than human fingertips, according to a study published in the Journal of Experimental Biology.
The sensors' function had not been known previously.
"People had fantastical ideas of what [the sensors] could do," said researcher Duncan Leitch, a graduate student in the neurosciences program at Vanderbilt University. "We tested the different possibilities to see how they actually work."
In conducting research, Leitch said that he was granted special research permission from the state of Tennessee to collect the alligators and crocodiles to study.
With his graduate advisor, Ken Catania, the two studied the external anatomy of the domes on the face of American alligators and on the faces and bodies of Nile crocodiles, which measured approximately 1 millimeter across, before cutting them open to look at the branches of nerves within.
Leitch said there were thousands of specialized nerve endings within the sensors along the jaw area and body that were similar to the ones humans have for the sense of touch.
To validate the sensitivity function, Leitch conducted a series of tests to see what the sensors were triggered by.
While no neural activity was detected when the animals' domes were exposed to salt water or electric fields generated by batteries, Leitch had success using plastic fibers typically used to test human thresholds of touch.
"When I touched each organ, they were as sensitive as the very finest of my touch fibers," said Leitch. "This surpasses what our own fingertips would detect."