Trunk compact, generally pear-shaped (Oikopleurinae), sometimes laterally compressed or dorso-ventrally depressed (Bathochordaeinae). Endostyle straight (Oikopleurinae-trunk). Spiracles opening into the rectal region. Esophagus entering the stomach from above or laterally. Stomach formed by many small and a few large gland cells. Tail several times as long as the trunk.
Subfamily Oikopleurinae Lohmann, 1896
Subfamily Bathochordaeinae Lohmann, 1933