Millipedes have two pairs of short legs on each body segment, a rounded body, and a hard external skeleton. Their legs are tucked under the body and difficult to see. The number of body segments varies with the species (estimated in the range of 10,000 species), but the number of pairs of legs generally ranges between 40 and 400. Centipedes have only one pair of legs on each body segment; these are easily spotted sticking out from their flattened bodies. The number of body segments varies with the species (estimated in the range of 8,000 species), and the pairs of legs vary from 15-177, plus or minus one. Centipedes have an odd number of pairs of legs; the last pair trails behind the body. Centipedes have less legs, but they are faster, have venom, have creepy mouth parts that tear through their food, and one of the most painful bites in the arthropod world.