Pronunciation: IN-tra-vert

Etymology: Introvert is derived from two Latin roots that mean on the inside (intro) and turn (versus).

An introvert is an eversible proboscis-like structure of loriciferans, priapulids, sipunculans, and bryozoans. The organ everts through hydrostatic pressure.

The introvert of the loriciferan, below, is the cone sticking out of the anterior end of the animal.

By Jack R. Holt. Last revised: 01/02/2009