Active camouflage with lichens in a terrestrial snail, Napaeus (N.) barquini Alonso and Ibáñez, 2006 (Gastropoda, Pulmonata, Enidae).

Napaeus barquini Alonso and Ibáñez, 2006, from La Gomera, Canary Islands, lives most commonly on open rock faces covered with crustose lichens. In living specimens, the surface of the shell is covered with a lichen layer that is arranged in the form of protuberances, thereby considerably altering the appearance of the shell. Some of these protuberances may even extend beyond the tip of the shell. The way that these lichens are positioned on the shell and the manner in which they adhere were investigated. The snail grazes lichen material from the substrate and applies it to the surface of its shell in a standardized pattern of movements. The snail uses its mouth to place the moist material onto the shell and to form it into protuberances that adhere as they dry out. To do this, Napaeus barquini extends its body far beyond the shell margin so that it can reach the entire outer surface of the shell and cover it with protuberances, presumably as camouflage.