Ancula pacifica

This goniodorid nudibranch is translucent white in color with orange lines on the body. There is a mid dorsal line and lines along the pallial margin, which may be continuous or interrupted. The pre-rhinophoral papillae and gills are tipped with orange and there is a line of orange pigment along the ridge of the tail. There are 4-14 club-shaped extra-branchial papillae which are translucent white with orange or yellow tips. Small papillae with orange tips typically occur between larger papillae with pale yellow tips.^[2] Individuals without the lines on the body occur in some populations. Although currently considered to be a synonym of the European species Ancula gibbosa there are significant differences in color and shape of the extra-branchial papillae and this is probably a distinct species.

Ancula pacifica probably feeds on Entoprocta which often grow on hydroids, bryozoa and other living substrata.