Crab lice, or Pthirus pubis, are tiny "crabs" less than 2 mm long. They can easily go unnoticed, but eventually make their presence felt by intense itching, the result of hypersensitivity to their saliva as they feed on their unfortunate host's blood. Crab lice get their appellation from their general appearance: they possess a more or less crab-shaped body and large claws, albeit on their hind legs, with which they cling to hair. Though they favor their namesake genital habitat, they may also migrate to other regions endowed with coarse hair, such as the limbs, underarms, beard, mustache, and even eyelashes. Unlike their â  body louseâ   cousins, crabs are not considered to be a major health hazard, as they are not a significant vector for any disease, though that is little consolation to their hosts. Giantmicrobes are based on actual microbes, cells, organisms and other critters, only 1,000,000 times actual size!