Imma Perfetto
Cosmos science journalist
Scientists have known for a while that the scale patterns found on the skin of a crocodile’s face and jaws doesn’t form due to genetic mechanisms. Instead, they’re produced by mechanical processes.
Now, a new Nature study has described that process, finding that the scales self-organise through compressive folding.
This occurs because the skin grows faster than the underlying bone and because of the differing stiffness of the skin’s dermis and epidermis layers.
The researchers conducted experiments in Nile crocodile (Crocodylus niloticus) embryos and showed that by increasing the skin’s stiffness and growth they could produce significantly more convoluted head skin patterns.
They validated their findings by creating a 3-dimensional growth model that can reproduce normal crocodile skin patterning.
“Overall, we demonstrate that evolution has produced 2 ways of generating crocodilian scales: chemical Turing instabilities (body scales) and mechanical instabilities (head scales),” the authors write in the paper.
“We suggest that the diversity of head-scale patterns among crocodilian species results from evolutionary changes in simple mechanical parameters, such as differential growth and material properties of the dermis versus the epidermis.”
