Microscopic fissures carve through the hides of African bush elephants. New research reveals that these crevices arise from tiny lumps beneath the animals’ unusually dry skin.
African bush elephants (Loxodonta africana) lack the oil and sweat glands that many other mammals use to keep skin moist and cool. Instead, these elephants bathe in water and mud, which collect in channels etched into the animals’ exceptionally tough skin. But the origin and development of these channels has remained unknown.
Michel Milinkovitch at the University of Geneva in Switzerland and his colleagues removed the fissured outermost layer, or stratum corneum, from samples of preserved elephant skin to reveal a deeper layer covered with millimetre-high mounds.
The team took microscopic images and micro-computed-tomography scans to design a computer model of the skin layers. The results showed that the accumulation of layers of deeper skin as an elephant ages forces the brittle stratum corneum to bend around the mounds until it cracks. The cracks then join to form channels that help the animals to stay cool.