Fig. 1
From: Locally-curved geometry generates bending cracks in the African elephant skin
Morphology of the African bush elephant’s (Loxodonta africana) skin. In addition to a, b centimetre-scale wrinkles and folds, African elephants exhibit c a network of narrow (~100 μm) channels (here, on the forehead of a juvenile animal). Previous research shows that these structures help the animal retain water and mud on its skin. d, e A patch of forehead skin before (d) and after (e) the mechanical extraction of the stratum corneum. In e, the narrow channels (white dotted lines) are no longer visible because they are confined to the extracted skin layer; note that the stratum corneum channels are confined in between papillae. The circled hair on both pictures serve as guides to the eye. f Mesh generated from the data of a micro-CT scan of a patch of skin without stratum corneum and colour-coded by height, showing the intricate three-dimensional surface geometry of the animal’s papillae. g A patch of skin from the forehead of an Asian elephant. Even though the pattern of papillae is present, narrow channels are not observed. Scale bars: a ∼50 cm; b ∼7 cm; c 7.5 mm; d 2.5 mm; e 2.5 mm; f 1 mm; g 5 mm
