Kingdom: Animalia

Phylum: Chordata

Class: Appendicularia

Order: Copelata

Family: Oikopleuridae

Genus: Oikopleura

Species: O. dioica


This is a small appendicularian usually between 0.5 and 1.0 mm but may reach 1.3 mm. They have an an ovoid trunk and a narrow tail, the length of the tail is about four times the body length. In this species the sexes are separated (which is not the case in all other known species of Appendicularia). Ovary or testis present at the posterior side of the trunk.  The endostyle is rather voluminous, posteriorly prolongated to just near the anus. The buccal glands are small and spherica. The right stomach lobe forms a cloacal sac behind the entrance to the intestine. It have a semi-cosmopolitan, neritic species from warm and temperate waters. Atlantic, Indian and Pacific Oceans. Also present in Mediterranean Sea and Red Sea. From all Appendicularia, Odioica is the most eurytherm and euryhaline species.