Trochophore

File:Trocofora.svg

The anatomy of a trochophore
A - episphere
B - hyposphere
1 - ganglia
2 - apical tuft
3 - prototroch
4 - metatroch
5 - nephridium
6 - anus
7 - protonephridia
8 - gastrointestinal tract
9 - buccal opening
10 - blastocoele

A trochophore (Template:IPAc-enTemplate:RefnTemplate:Refn) 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 Template:Wikt-lang (Template:Grc-transl), meaning "wheel", and Template:Wikt-lang (Template:Grc-transl) — or Template:Wikt-lang (Template:Grc-transl) —, 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

File:Pomatoceros lamarckii development.jpg

Bright-field microscope image of trochophore of annelid Pomatoceros lamarckii (family Serpulidae)

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.

File:Haliotis asinina trochophore.jpg

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

File:Polyplacophora ontogeny.jpg

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