Trochophore

A trochophore (; also spelled trocophore) is a type of free-swimming planktonic marine larva with several bands of cilia.
By moving their cilia rapidly, a water eddy is created. In this way they control the direction of their movement. Additionally, in this way they bring their food closer, in order to capture it more easily.
Occurrence.
Trochophores exist as a larval form within the trochozoan clade, which include the entoprocts, molluscs, annelids, echiurans, 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.
Etymology.
The term "trochophore" derives from the ancient Greek (), meaning "wheel", and () — or () —, meaning 'to bear, to carry', because the larva is bearing a wheel-shaped band of cilia.
Feeding habits.
Trochophore larvae are often planktotrophic; that is, they feed on other plankton species.
Life cycle.
The example of the development of the annelid "Pomatoceros lamarckii" (family Serpulidae) shows various trochophore stages (image: D-F):<br>
D - early trochophore ;<br>
E - complete trochophore ;<br>
F - late trochophore ;<br>
G - metatrochophore.