A new study has shed light on how the pattern of scales develops on a crocodile's face and jaw. In mammals, birds and even many reptiles, the pattern of hair, feathers and scales develops from genetically-controlled processes. But in crocodiles, the scales emerge when the skin stretches and cracks. During embryonic development, the crocodile's face and jaw grow rapidly and this stretches the tough skin to the cracking point.
Another feature of crocodile skin is that it has small dome-shaped pressure receptors scattered across its surface. These receptors enable the crocodile to sense surface pressure waves and in doing so to detect prey easily, even in total darkness. As the skin stretches, it cracks and forms scales around the pressure receptors. The result is the formation of many polygonal-shaped scale.
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