Europe also has a number of insectivores including hedgehogs (Erinaceus europaeus), shrews (e.g. Sorex araneus) and moles (e.g. Chrysochloris asiatica). The spines of a hedgehog are no more than modified hairs. In many parts of the world shrews are abundant animals and although small, are very ferocious, attacking any small creature they encounter including one another. To sustain themselves, they have to eat great quantities of earthworms and insects every day. Among the shrew is one of the smallest mammals, the pygmy shrew (Suncus etruscus) which weighs only 1.5 to 2.5 g). Shrews communicate with one another by shrill high pitched squeaks. They also produce noises of a frequency that is far above the range of our ears, their eyesight is very poor and there is some indication that they use these ultra sounds as a simple form of echo location.