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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.



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.


References in periodicals archive ?
Giant clams are typical of bivalve molluscs, going through trochophore, veliger, and pediveliger stages before completing metamorphosis into juveniles (Lucas 1988).
Although we did not witness complete blastopore closure, as few individuals were preserved between the gastrula and trochophore stage, these cell extensions may play a role in the fate of the blastopore.
Generally, the larval development of molluscs started with a basic stage of trochophore and then progressively develop into lecithotrophic or planktotrophic veliger larvae, which are characterized by the formation of the velum.
Suspension feeding by marine invertebrate larvae: clearance of particles by ciliated bands of a rotifer, pluteus, and trochophore.
Understanding the hypothesized repeated losses of both spiral cleavage and trochophore larvae in the Lophotrochozoa (Dunn et al.
A few annelid larvae are so highly derived--assuming that the trochophore in the sense of Rouse (1999) is indeed a plesiomorphic form--that they are not immediately recognizable as manifestations of the trochophore ground plan.
At 12 and 24 h after fertilization, triplicate water samples (1 mL) were used to estimate the number and size of trochophore and veliger larvae, respectively.
and tiny feeding trochophores are released (Nielsen, 1971).
Homology of ciliary bands in spiralian trochophores.
Nemerteans, commonly known as ribbon worms, are a fascinating but often ignored phylum of marine invertebrates, closely related to coelomate protostome animals with spiral cleavage and trochophore larvae, such as annelids and molluscs.