Lophotrochozoa

Lophotrochozoa Fossil range: Early Cambrian - Recent
Caribbean Reef Squid or Sepioteuthis sepioidea is a complex lophotrochozoan.
Scientific classification
Kingdom: Animalia Subkingdom: Eumetazoa (unranked) Bilateria Superphylum: Lophotrochozoa
Phyla
Sipuncula Hyolitha † Nemertea Phoronida Bryozoa Entoprocta Brachiopoda Mollusca Annelida Echiura

The Lophotrochozoa ("crest-bearing animals") are one of two or three major groups of protostome animals. The taxon was introduced in the 1990s as a result of studies of the evolution of small-subunit ribosomal RNA (rRNA) supporting the monophyly of the phyla listed in the infobox shown at right.Philippe, Hervé, Nicolas Lartillot1 and Henner Brinkmann. (2005) "Multigene Analyses of Bilaterian Animals Corroborate the Monophyly of Ecdysozoa, Lophotrochozoa, and Protostomia." Molecular Biology and Evolution 2005 22(5):1246-1253; doi:10.1093/molbev/msi111. Found at [1]

Trochozoans produce trochophore larvae, which have two bands of cilia 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.

Other phyla are included on the basis of molecular data.

References

External links

• UCMP-Lophotrochozoa introduction

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