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Lophotrochozoa
From Wikipedia, the free encyclopedia
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 Caribbean Reef Squid or Sepioteuthis sepioidea is a complex lophotrochozoan.
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Trochozoa Lophophorata |
The Lophotrochozoa are one of two or three major groups of protostome animals. They include the phyla listed in the infobox shown at right.
Trochozoans produce trochophore larvae, which have two bands of cillia around their middle. Previously these were treated together as the Trochozoa, together with the arthropods, which do not produce trochophore larvae but were considered close relatives of the annelids because they are both segmented. However, they show a number of important differences, and the arthropods are now placed separately among the Ecdysozoa.
The Lophophorata are united by the presence of a lophophore, a fan of ciliated tentacles surrounding the mouth, and so were treated together as the lophophorates. They are unusual in showing radial cleavage, and some authors considered them deuterostomes, before RNA trees placed them together with the trochozoans. The exact relationships between the different phyla are not entirely certain. However, it appears that neither the lophophorates nor the Trochozoa are monophyletic groups by themselves, but are mixed together.
