A trochophore (/ˈtroʊkəˌfɔːr, ˈtrɒ-, -koʊ-/;^[1][2]) is a type of free-swimming planktonic marine larva with several bands of cilia.

By moving their cilia rapidly, they make a water eddy to control their movement, and to bring their food closer in order to capture it more easily.

Trochophores exist as a larval form within the trochozoan clade, which include the entoprocts, molluscs, annelids (including echiurans and sipunculans) and nemerteans. Together, these phyla make up part of the Lophotrochozoa; it is possible that trochophore larvae were present in the life cycle of the group's common ancestor.

The term trochophore derives from the ancient Greek τροχός (trókhos), meaning "wheel", and φέρω (phérō) — or φορέω (phoréō) —, meaning 'to bear, to carry',^[3] because the larva is bearing a wheel-shaped band of cilia.

Trochophore larvae are often planktotrophic; that is, they feed on other plankton species.

The example of the development of the annelid Pomatoceros lamarckii (family Serpulidae) shows various trochophore stages (image: D-F):
D - early trochophore ;
E - complete trochophore ;
F - late trochophore ;
G - metatrochophore.