Zoology: Cracking the reason for channels on elephant’s skin

The network of channels on the surface of the skin of the African bush elephant is a consequence of physical cracks during epidermal growth according to a study in Nature Communications this week.

Physical cracking patterns often occur in non-living materials, but are rare in biological systems. The skin of the African elephant is deeply sculpted by an intricate network of micrometre-wide interconnected crevices and these channels facilitate retention of five to ten times more water than a flat surface. This enhances the effectiveness of thermal regulation as well as protecting against parasites. However, how these channels form remains unclear.

Using microscopy and physics-based modelling, Michel Milinkovitch and colleagues propose that the channels are fractures of the skin's outermost layer - the stratum corneum. The authors suggest that the channels form due to physical cracks caused by the bending stress of the progressively growing epidermis. This is supported by the observation that new-born elephants do not have these channels on the skin.

Further studies are required to understand why there is a lack of a cracking pattern on the skin of Asian elephants and to understand the physiological characteristics of the African elephant’s skin cells.