Many insects, including bees, roaches, butterflies, grasshoppers and ants have six legs. While it is possible for mammals and other land-dwelling animals to be born with six legs, it is extremely rare.
Six-legged insects are classified as arthropods, but there are other arthropod species that have more than six legs, including arachnids, or spiders, and centipedes. Crustaceans, diplopods and hexapods are also within the arthropod classification. The general characteristics of an arthropod are an exoskeleton, a dorsal blood pump, a segmented body, a ventral nerve cord, jointed limbs and bilateral symmetry. The six legs support and enable what is referred to as the tripod gait.