Centipedes (Class Chilopoda)
Centipedes are arthropods, but distinctively they are myriapods (a separate subphylum characterized by the body plan of head followed by elongated body with many legs), and among this set of 4 taxonomic classes they are Chilopoda -- they have a distinct head, one pair of legs per leg-bearing segment, and the first pair of legs modified as poison fangs. The trunk has at least 16 segments, with the last pair being the longest.
In our area, The Giant Desert Centipede (Scolopendra heros) reaches a length of almost 8" (40 cm), with 20 pairs of legs or more. They are brightly colored in brownish yellows, with red, orange, or green, with a dark bluish head,. They are mainly nocturnal predators, who burrow under soil, litter, or rocks, and move out very rapidly to kill prey as diverse as small arthropods, lizards, and even mice. To humans, the Centipede's bites are roughly equivalent to a wasp's sting in effect, with swelling and occasional slow healing of the wound.
We have found that large Centipedes move too fast to be captured readily by a still camera. The image below (a specimen collected by Madison Baker) has been frozen, hence its unnatural disposition. The head is to the left, the rear feet (which possess spinelike teeth, used in defence) to the right. We count 22 pairs of legs total.
In the early springtime, young ones can be found from time to time on rocks that have been overturned. This delicate Scutigera sp. below, seen in March 2005 in Hot Springs Canyon, is no more than an inch in length. These also move quickly, but stop more often to hide:
Centipedes court, with male and female forming a ring, and females guard their eggs until the young have hatched and dispersed.