Those are camel spiders - we used to get them in Saudi. They're not actually spiders, they're a different family (solpugida I think it was). They run fricking fast, but they don't actually attack you - they're just trying to get into shadows to get under things. And I don't recall anyone being bitten by one, but the arabs claimed that they could eat half your face away if you were asleep, before you noticed. We used to sleep in the desert and I still have a (more or less) face - and we used to sleep in the open and find them about, so don't know about the veracity of that one.
