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n. pl.1.(Zool.) A peculiar larval form of Phoronis, a genus of marine worms, having a circle of ciliated tentacles.
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The actinotrocha is the feeding larval form of the lophophorate phylum Phoronida.
The phoronid actinotrocha differs strikingly from both spiralian and deuterostome larval forms in its large, mobile, and muscular oral hood, present throughout growth and development of the larva [ILLUSTRATION FOR FIGURE 1 OMITTED].
Our first observations were of a single actinotrocha that was collected from the coastal plankton off Plymouth, England (English Channel), in June 1989.
Zimmer described the anatomy of this larva in some detail under the provisional identification of Actinotrocha A.
Particles were carded past the actinotrocha in the current produced by the lateral cilia of the tentacles and a posterior ring of longer cilia (the telotroch).
When an actinotrocha lifted and lowered its oral hood in rapid succession, a particle moved proximally with each lift and distally with each lowering [ILLUSTRATION FOR FIGURE 5 OMITTED].
The largest particle found in the stomach of an actinotrocha of P.
The muscular oral hood of the actinotrocha provides a mechanism for capturing large prey, but such prey can also be captured by some ciliary mechanisms.
Is there evidence that the actinotrocha has evolved an unusual capability in any of these three components of clearance rate, as a possible result of transport aided by a hood lift?
The actinotrocha might achieve a faster swimming and feeding current by additional propulsion from its telotroch, a posterior ring of longer cilia (Nielsen, 1987).