July 4, 2013 – Researchers in Switzerland have discovered that crocodiles and alligators have special organs in their scaly skin that are not only sensitive to heat, cold, and touch, but chemicals in the environment as well!
These organs are called integumentary sensory organs (ISOs), and are only found in crocs, alligators, and other animals in the crocodilian order like caimans and gharials. ISOs are as sensitive as our fingertips and they are found on the heads of these animals.
"It is this transformation of a diffuse sensory system, such as we have in our own skin, into ISO which has allowed crocodilians to evolve a highly armoured yet very sensitive skin," said Michel Mikinkovitch, the lead researcher of the study from the University of Geneva.
ISOs help these animals analyze surface pressure waves in water, which helps them find prey when there is no light. Since they are cold blooded they have to bask in the sun to keep their bodies warm enough –the heat sensitivity of their ISOs helps them recognize when they are warm enough and can go lounge in the shade for awhile. Their ISOs' ability to also detect chemicals likely helps them choose their habitats as well.
The researchers studied how ISOs grow and are used on Nile crocodiles and caimans. They found that the ISOs develop before they are born and even before their scales begin to grow on their skin! They also found that Nile crocodiles have ISOs all over their bodies, making them extra sensitive to heat, cold, touch, and environmental chemicals.