Trochophore

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.

Occurrence

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.

Etymology

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.

Feeding habits

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

Life cycle

Bright-field microscope image of trochophore of annelid Pomatoceros lamarckii (family Serpulidae)^[4]

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.

9-hour-old trochophore of the marine gastropod Haliotis asinina (sf - shell field)^[5]

Ontogeny of the Polyplacophora: First image shows the trochophore, second shows the stadium in metamorphosis, third is a juvenile (scanning electron microscope: SEM)