Oikopleura dioca , the appendicularians are hermaphrodites and the gonads occupy a relatively large part of the body in mature individuals, sometimes producing the curvature of the trunk of the animal. The length of the tail is three times the length of the body. The tail has a neural chord or notochord, covered by a well-developed musculature. On both sides of the tail there could be subchordal and amphichordal cells, which are absent in some species, depending on the family.