Trochophore

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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 (/ˈtrkəˌfɔːr, ˈtrɒ-, -k-/;[1][2] also spelled trocophore) 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, to capture it more easily.

Occurrence[edit]

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[edit]

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[edit]

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

Life cycle[edit]

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)

References[edit]

  1. ^ "Trochophore". Oxford Dictionaries UK English Dictionary. Oxford University Press. n.d. Retrieved 2016-01-21.
  2. ^ "Trochophore". Dictionary.com Unabridged (Online). n.d. Retrieved 2016-01-21.
  3. ^ Bailly, Anatole. "Greek-french dictionary online". www.tabularium.be. Retrieved 2017-01-24.
  4. ^ 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. PMC 1615870. PMID 17032451.
  5. ^ 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. PMC 2034539. PMID 17845714.

External links[edit]