Ca. 8 cm long. It can reach 18 centimeters in length and have different colourings, from brown to black, through orange, yellow or greenish. However, the black Arion rufus is brown in its juvenile stadium. The mucus that it segregates allows it to keep humid and protect itself from its potential predators because of its bad taste. In spite of this, some mammals do not despise it, like the mouse or the badger, birds or amphibians, like the frog. On the right side, near the head, it has the pneuomosta or orifice through which it breathes. With nocturnal customs, the slug is omnivorous, nourishing itself from vegetables, even in process of decomposition, fungi and carrion. It is very similar to the black slug, A. ater. They can interbreed. The reproductive process takes place with a couple but, in the absence of this, can be hermaphrodite.
Humid woody areas. Spotted at a beech forest. Parque Natural de Saja-Besaya
Camera Model: NIKON D300. Exposure Time: 1/125 sec.; f/5.6; ISO Speed Rating: 800. Exposure Bias: 0 EV. Focal Length: 300.0 mm. No flash fired