Scorpion

The scorpion, a venomous arachnid of dry country whose sting can kill, was met in the ancient world with a mixture of fear and reverence. In Egypt it was embodied in the goddess Serqet or Selket, shown with a scorpion on her head, a protector of the dead who guarded one of the four canopic shrines, and paradoxically a guardian against the very venom she personified. The myth of Isis tells how the goddess, hiding with the infant Horus in the marshes, was escorted and protected by seven scorpions, and how the sting of one, meant for Isis, struck a child instead and was healed by her magic, the scorpion as both danger and, mastered, defence.

A genuinely strange fact about the living animal now underlies part of its old reputation for uncanny power: scorpions fluoresce a vivid blue-green under ultraviolet light, a property of a thin layer in their exoskeleton discovered by researchers only in the twentieth century and still not fully explained, since the effect works even in scorpions blind from birth. Modern medicine has in turn found real use for scorpion venom: a compound called chlorotoxin, isolated from the deathstalker scorpion, is being developed as a tumour-marking agent that binds selectively to certain brain cancers, an active area of clinical research rather than a folk remedy.

In Mesopotamian myth scorpion-men, half-human and terrible, guard the mountain gate through which the sun rises and sets, and the hero Gilgamesh must pass them on his journey to the edge of the world. The scorpion is one of the oldest of the zodiac signs, Scorpio, and Greek myth set it in the sky as the creature that killed the giant hunter Orion, sent, in one telling, by the goddess whose modesty or whose creatures he had offended, so that the two constellations were placed on opposite sides of the sky, Orion forever setting as Scorpius rises. Guardian and killer, protector and poison, the scorpion carries a consistently double-edged symbolism of death held at bay.

Scorpions are also one of the true living fossils among arthropods: fossil scorpions are known from the Silurian period, more than four hundred million years ago, among the very earliest animals to move onto land, and their basic body plan has changed remarkably little since, so the animal feared and revered across the ancient Near East was already, by the standards of its own antiquity, an ancient creature. The scorpion's fearsome reputation outruns the biology: of roughly two and a half thousand known scorpion species, only around thirty, concentrated in the family Buthidae, carry venom dangerous enough to kill a healthy adult human, and most of the world's scorpions deliver a sting no worse than a wasp's, a divergence between ancient dread and modern toxicology worth noting beside the guardian-and-killer symbolism above.