Threatened arthropods United States, and IUCN Red List for international purposes. Only a tiny fraction of the planet's endangered arthropods are formally recognized as such, as no one has ever evaluated the conservation status of the vast majority of arthropod species. It is difficult to estimate the total number of endangered arthropod species, since many of the taxa themselves have not been recorded. For example, in North America the estimated number of insect species exceeds 163,000, of which only about two thirds are taxonomically known. An even greater discovery awaiting, over 72 percent of North American arachnids are yet to be named
Terrestrial locomotion The most diverse group of animals on earth, the insects, are included in a larger taxon known as hexapods, most of which are hexapedal, walking and standing on six legs. Exceptions among the insects include praying mantises and water scorpions, which are quadrupeds with their front two legs modified for grasping, some butterflies such as the Lycaenidae (blues and hairstreaks) which use only four legs, and some kinds of insect larvae that may have no legs (e.g., maggots), or additional prolegs (e.g., caterpillars). Spiders and many of their relatives move on eight legs – they are octopedal. However, some creatures