The six-eyed sand spider is one of the most venemous spiders in the world.

Wikipedia - Everything you always wanted to know about the Six eyed sand spider.

This spider buries itself in the sand and strikes from ambush at prey that wanders too closely. Sand particles adhere to cuticles on its abdomen, thus acting as a natural camouflage if uncovered. If disturbed, it will run a short distance and bury itself again. The six-eyed spider has a poor sense of direction, unlike other species of spiders. On top of this it can survive a year without a meal or even a drop to drink, making it a patient hunter.

Toxicology studies have demonstrated that the venom is particularly potent, with a powerful hemolytic/necrotoxic effect, causing blood vessel leakage, thinning of the blood and tissue destruction. Treatment should be directed, as with all cytotoxic bites, at prevention of secondary infection and combating Disseminated intravascular coagulation (DIC) if it develops. No anti-venom exists for it.

The six-eyed sand spider is a member of the family Sicariidae found in deserts and other sandy places in southern Africa.