Kinorhyncha is a phylum of small marine invertebrates found at all depths in mud or sand as part of the meiobenthos. Kinorhynchs are limbless animals having a body made up of a head, neck, and an eleven-segmented trunk. Except for the panarthropoda, they are the only Ecdysozoa members with a segmented body. Juveniles have eight or nine segments, depending on the genus, with the last two or three added later in development. They, like other ecdysozoans, lack external cilia and instead contain a number of spines along the body, as well as up to seven circles of spines around the head. These spines are employed for locomotion by withdrawing the head and pushing forward, then holding the substrate with the spines as the body draws up. Depending on the species, kinorhynchs eat diatoms or organic substances found in the mud. The mouth is placed at the apex of the head in a conical structure and opens into a pharynx and then an oesophagus, both of which are lined by cuticle. A ventral nerve cord with one ganglion in each segment and an anterior nerve ring enclosing the pharynx comprise the nervous system. Smaller ganglia can also be seen in the lateral and dorsal regions of each segment, although they do not form discrete cords. To provide a sensation of touch, some species have simple ocelli on the head, while all species have tiny bristles on the body.