The European mole (Talpa europaea) is a mammal of the order Eulipotyphla. It is also known as the common mole and the northern mole. This mole lives in a tunnel system, which it constantly extends. It uses these tunnels to hunt its prey. Under normal conditions the displaced earth is pushed to the surface, resulting in the characteristic molehills. It feeds mainly on earthworms, but also on insects, centipedes and even mice and shrews. Its saliva contains toxins which paralyze earthworms in particular. The European mole has a cylindrical body and is 11 to 16 cm (4.3 to 6.3 in) long, weighing 70 to 130 g (2.5 to 4.6 oz). Females are typically smaller than males. The eyes are small and hidden behind fur, while the ears are just small ridges in the skin. The fur is usually dark grey, but the actual range of colors is larger, as due to the subterranean habits there is no disadvantage in having off-colored fur. European moles with white, light grey, tan, taupe, and black fur have all been reported. While moles are typically found in tunnel systems, the European mole is not exclusively an underground dweller. In the spring and early summer when the young moles leave their mothers' burrows they must find new territories. This forces them to leave their burrows and they can either make new tunnel systems or enter existing systems. In the summer time, however, they are likely to burrow much more superficially. The superficial burrowing could be due in part to the soil that is much harder, which makes burrowing a greater challenge. T. europaea have also been found to spend a lot of time at the sides of drainage lines and streams but do not inhabit flooded or dry soils. However, dry areas do become important when their normal habitats become flooded. Factors such as the type of soil, vegetation present, and altitude have no effect on the areas that moles choose to inhabit. The one factor that does greatly influence the mole population in a specific area is the abundance of earthworms. In suitable urban greenspace, an area of 10 hectares is required for population persistence, and the number of mole territories increases with available habitat.