An order of nematodes comprising the single superfamily Oncholaimoidea. These nematodes are principally marine and brackish-water forms with alleged predaceous and carnivorous feeding habits. The external amphidial aperture is an oval or a widened ellipse. Generally, the stoma is armed with one dorsal tooth and two subventral teeth, and its wall may be further fortified with transverse rows of small denticles. The stoma is divisible into the cheilostome (secondary blastocoel invagination) and the esophastome (primary blastocoel invagination). In some species the stoma of the adult male is collapsed or indistinct. The cephalic sensilla are in two whorls: one is circumoral and composed of six papilliform sensilla; the second combines the ancestral two whorls of six and four into a single whorl of ten setiform sensory organs. In some forms these sensilla are papilliform. The cylindrical-to-conoid esophagus may exhibit a series of muscular bulbs posteriorly. The cuticle is generally smooth, and over the length of the body there are scattered sensory setae or papillae.