Author: Jan Scholten
English: Gnathostomulids; Jaw worms.
Clades: Platyzoa; Protostomia; Animals.
Nearly microscopic marine animals, ± 1 mm long; ciliated epidermis, one cilium per cell; no body cavity; no circulatory or respiratory system; hermaphrodite, possessing an ovary and a testis; specialized, muscular jaw, scraping smaller organisms off of the grains of sand; seabed mud habitat; bilaterally symmetrical pharynx; complex cuticular mouth; appear closely related to rotifers and their allies, together making up the Gnathifera.
Genera: 100 species, many more as yet undescribed.
Filospermoidea: very long and are characterized by an elongate rostrum.
Bursovaginoidea: presence of a penis and a sperm-storage organ called a bursa.