Trochophore

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 (/ˈtroʊkəˌfɔːr, ˈtrɒ-, -koʊ-/;[1][2] 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 τροχός (trókhos), meaning "wheel", and φορέω (phoréō), meaning 'to bear, to carry',[3][4] 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)[5]

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)[6]
Ontogeny of the Polyplacophora: First image shows the trochophore, second shows the stadium in metamorphosis, third is a juvenile (scanning electron microscope: SEM)

References

  1. ↑ "Trochophore". Oxford Dictionaries. Oxford University Press. Retrieved 2016-01-21.
  2. ↑ "Trochophore". Dictionary.com Unabridged. Random House. Retrieved 2016-01-21.
  3. ↑ Bailly, Anatole (1981-01-01). Abrégé du dictionnaire grec français. Paris: Hachette. ISBN 2010035283. OCLC 461974285.
  4. ↑ Bailly, Anatole. "Greek-french dictionary online". www.tabularium.be. Retrieved 2017-01-24.
  5. ↑ McDougall, Carmel; Chen, Wei-Chung; Shimeld, Sebastian M.; Ferrier, David E. K. (2006). ""The development of the larval nervous system, musculature and ciliary bands of Pomatoceros lamarckii (Annelida): heterochrony in polychaetes."". Frontiers in Zoology. 3 (1): 16. doi:10.1186/1742-9994-3-16.
  6. ↑ Jackson, Daniel J.; Wörheide, Gert; Degnan, Bernard M. (2007). "Dynamic expression of ancient and novel molluscan shell genes during ecological transitions". BMC Evolutionary Biology. 7 (1): 160. doi:10.1186/1471-2148-7-160.
  • Nielsen, Claus (2018-07-01). "Origin of the trochophora larva". Royal Society Open Science. 5 (7): 180042. doi:10.1098/rsos.180042. ISSN 2054-5703.
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