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(invertebrate zoology)
A generalized but distinct free-swimming larva found in several invertebrate groups, having a pear-shaped form with an external circlet of cilia, apical ciliary tufts, a complete functional digestive tract, and paired nephridia with excretory tubules. Also known as trochosphere.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



the free-swimming larva of some annelid worms (polychaetes), echiuroids, sipunculids, and some mol-lusks. The microscopic body is fringed by one or more bands of cilia that facilitate locomotion in water. A preoral band or proto-troch is highly characteristic of the organism. At the upper pole of the trochophore is the sense organ, a parietal plate with a tuft of cilia and a group of nerve cells. The mouth is located on the ventral side, behind the prototroch. The intestine consists of a gullet, middle gut, and posterior gut. The anal opening is at the posterior pole. The excretory organs are a pair of protone-phridia. Alongside the intestine is a pair of primary mesodermal cells (mesoblasts), which produce a pair of mesodermal bands by repeated division. As a result of further development the trochophore acquires bristles, and its mesodermal bands become segmented, forming a series of paired coelomic sacs. The larva is then called a metatrochophore or nectochaeta.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The prototroch and metatroch of the trochophore were visible and beating throughout the periods of observation.
In the present study, embryonic development to the trochophore stage occurred in less time (17.5 h after fertilization) than has been reported for Panopea globosa in the northern Gulf of California under the same temperature regime (20 h after fertilization, at ~22[degrees]C) in the laboratory (Ferreira-Arrieta et al.
The first [beta]1-like integrin-positive signal appeared at the early trochophore stage (19 hpf) in 5% of the Mytilus larvae.
The percentages of the intermediate stages (trochophore) for the DELTA treatments were always lower than the control (P < 0.05).
Ten ml of algae solution in exponential phase, from a 21 mass culture, were added every three days to the aquarium containing 200 trochophore larvae.
Since the common ancestor of all Trochozoa likely possessed a trochophore larva, the group has been the longtime focus of extensive comparative anatomical, systematic, evolutionary, and phylogenetic studies (Naef, 1928: Beklemishev.
Hybrids initially developed faster than pure-strain larvae during the trochophore and veliger stages, but developmental differences evened out with the onset of metamorphosis.
Suspension feeding by marine invertebrate larvae: Clearance of particles by ciliated bands of a rotifer, pluteus, and trochophore. Biological Bulletin 142:516-518.
Samples of 1 mL at 5, 10, 15, and 30 min during the first 3 h then later each 30 min in the subsequent 6 h, and later each hour were measured to determine the embryogenic stage until the trochophore and D-larvae appeared.
From trochophore to pilidium and back again--a larva's journey.
Oxygen consumption rate ([??][O.sub.2]) of hybrids is dependent on developmental stage and it has been suggested that differences in [??][O.sub.2] across the different stages (embryonic, trochophore larvae, veliger larvae, and settling larvae) are attributable to differences in activity level (Alter et al.