Crocodilians are more sensitive to touch than humans

Researchers in the US have discovered that the dome-shaped dots along the jaws of alligators and crocodiles are in fact more sensitive to pressure and vibration than human fingertips. Previously it was believed these freckle-like features were for camouflage, but they have turned out to be much more complex.

The neuroscientists who conducted the study suggest the sensitive spots play a major part in the aquatic reptiles' impressive reaction times when hunting. The technical name for the spots is integumentary sensor organs (ISOs).

Scientists over the years have speculated over the spot’s functions – from secreting oil to detecting electrical fields. However, a study in 2002 suggested that they detected ripples made by water, which led to the latest research.

Co-author Duncan Leitch, of Vanderbilt University, Nashville, commented that the jaws of crocodiles seem to be unique and can almost be said to perform some of the tactile functions of human hands.
In the lab, Mr Leitch tested how the features reacted to a variety of stimuli. He found no reaction to salinity or electrical fields but touch was a key trigger.

He explained: "When I used a calibrated series of fibres to touch or tickle the [bumps], I found that they were responsive to forces finer than our own fingertips – a sensory system widely studied for its own sensitivity.”

“Although crocodilians are certainly not the ancestors to humans, it is interesting to see how different parts of their forebrain may have evolved to process different sensations," Mr Leitch continued. "One goal with a lot of this research is gaining a better understanding of how very different nervous systems have evolved to solve similar problems."