Common name: centipedes, Weri.
Centipedes have an ancestry dating back 420 million years to the late Silurian. They belong to the subphylum Myriapoda which includes Diplopoda, Symphyla, and Pauropoda. The oldest known fossil land animal is a Myriapod.[clarification needed] Being one of the earliest terrestrial animals, centipedes were one of the first to fill a fundamental niche as ground level generalist predators in detrital food webs. Today centipedes are abundant and exist in many harsh habitats.
Some people confuse centipedes with millipedes. Centipedes are the flat ones that move like lightning when disturbed. Millipedes are the cylindrical slow creatures that curl up in a spiral when threatened. Millipedes are detritivores, feasting on decaying vegetation.
Centipedes are elongate many segmented arthropods with many sets of long legs splayed out to the side. Centipedes might have fewer or more pairs of legs than the mythical 100, but they always have odd numbers of legs so you could never count an even 100. The centipedes are commonly 2-5 cm in size, although some tropical forms reach over 20 cm. Each segment of the body bears a single pair of walking legs; the total number of segments and pairs of legs can vary from fifteen to more than a 100. The segments of the body are covered with lightly sclerotized, leathery plates, connected to one another by the soft, pliable cuticle. The last legs differ in structure and function; often they are modified as genital appendages (gonopodes).
The remarkable and unique feature of centipedes is the large, robust, pincer-like appendages of the first segment following the head - the forcipules, also known as maxillipedes, or poison-claws. The forcipules are modified legs, which function as jaws; they are jointed, open and close in a horizontal plane, and end in sharp claws. The centipedes use forcipules to capture and poison their prey. The ducts of poison glands open near the tips of the claws. The forcipules are found in all Chilopoda and occur in no other arthropods.
The information above is from the "Guide to Soil Invertebrates" Massey University's website. For more information http://soilbugs.massey.ac.nz/chilopoda.php