A trochophore (; also spelled trocophore) is a type of free-swimming
plankton
Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...
ic marine
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
...
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
Trochophores exist as a larval form within the
trochozoa
The Trochozoa are a proposed Lophotrochozoa clade that is a sister clade of Bryozoa. The trochozoans clade include animals in six phyla: the Nemertea, the Annelida, the Cycliophora, the Mollusca, and the two Brachiozoa
Brachiozoa is a groupin ...
n clade, which include the
entoprocts,
molluscs,
annelids,
echiura
The Echiura, or spoon worms, are a small group of marine animals. Once treated as a separate phylum, they are now considered to belong to Annelida. Annelids typically have their bodies divided into segments, but echiurans have secondarily los ...
ns,
sipuncula
The Sipuncula or Sipunculida (common names sipunculid worms or peanut worms) is a class containing about 162 species of unsegmented marine annelid worms. The name ''Sipuncula'' is from the genus name ''Sipunculus'', and comes from the Latin ' ...
ns and
nemertea
Nemertea is a phylum of animals also known as ribbon worms or proboscis worms, consisting of 1300 known species. Most ribbon worms are very slim, usually only a few millimeters wide, although a few have relatively short but wide bodies. Many h ...
ns. Together, these phyla make up part of the
Lophotrochozoa
Lophotrochozoa (, "crest/wheel animals") is a clade of protostome animals within the Spiralia. The taxon was established as a monophyletic group based on molecular evidence. The clade includes animals like annelids, molluscs, bryozoans, brachi ...
; 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
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...
(), 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
''Pomatoceros lamarckii'' is a species of tube-building annelid worms which is widespread in intertidal and sub-littoral zones around the United Kingdom and northern Europe. They are found attached to firm substrates, from rocks to animal shell ...
'' (family
Serpulidae
The Serpulidae are a family of sessile, tube-building annelid worms in the class Polychaeta. The members of this family differ from other sabellid tube worms in that they have a specialized operculum that blocks the entrance of their tubes wh ...
) shows various trochophore stages (image: D-F):
D - early trochophore ;
E - complete trochophore ;
F - late trochophore ;
G -
metatrochophore
A metatrochophore (;) is a type of larva developed from the trochophore larva of a polychaete annelid
The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant sp ...
.
References
External links
*
{{Bivalve anatomy
Larvae
Lophotrochozoa
