United States Fish and Wildlife Service list of threatened and endangered arthropods species may be treated as endangered or threatened if it resembles in appearance a species which has been listed and enforcement personnel would have difficulty distinguishing between the listed and the unlisted species; if the effect of this difficulty is an additional threat to the listed species; and if such treatment of the unlisted species would improve protection for the listed species. United States Fish and Wildlife Service list of threatened and endangered arthropods List of threatened and endangered arthropods, including insects, arachnids, and crustaceans under the United States Endangered Species Act as of October 2013. Key to Listing Status
Annelid Annelids are members of the protostomes, one of the two major superphyla of bilaterian animals – the other is the deuterostomes, which includes vertebrates. Within the protostomes, annelids used to be grouped with arthropods under the super-group Articulata ("jointed animals"), as segmentation is obvious in most members of both phyla. However, the genes that drive segmentation in arthropods do not appear to do the same in annelids. Arthropods and annelids both have close relatives that are unsegmented. It is at least as easy to assume that they evolved segmented bodies independently as it is to assume that the ancestral protostome