An order of the tardigrades, the majority of whose genera have widely varied structure. Cephalic appendages having a sensorial function are present, as well as cirrus lateralis and clava. Pharyngeal pockets are strengthened by uninterrupted ridges, except in Pseudechiniscus islandicus, which has interrupted ones. Toes or claws are uniform in structure and completely separated from one another. A preanal gonopore is present; excretory glands are absent. This order of tardigrades is divided into two suborders, Arthrotardigrada and Echiniscoidea.