Sea scorpions and true scorpions are actually sister clades that both belong to a Subphylum known as Chelicerata, an ancient group of arthropods that first appeared in the oceans of the Cambrian Period.

子和真子实际上是姊妹进化枝， 都属被称为螯肢动物亚门的亚门，这是一种现在寒武纪洋中的古老节肢动物群。