lophotrochozoan

Lophotrochozoa is a major superphylum of animals within the protostomes. It is one of the two large clades that make up Spiralia, the other being Ecdysozoa. Molecular studies consistently recover Lophotrochozoa as a single monophyletic group, though the precise relationships among its constituent phyla remain debated.

The group comprises two broad lineages. The lophophorates include Brachiopoda, Bryozoa (Ectoprocta), and Phoronida, which feed using a lophophore, a crown of ciliated tentacles. The trochozoans include Mollusca and Annelida as well as several smaller phyla such as Sipuncula, Echiura, and Nemertea; many trochozoans have a trochophore-type larva in some life stages and exhibit a wide range of body plans, from wormlike to highly complex.

Ecology and evolution: Lophotrochozoans inhabit diverse environments, from marine and freshwater to terrestrial ecosystems. The fossil record is rich, with abundant brachiopods and molluscs documenting the group's early diversification. The clade includes species of major ecological and economic importance, such as many molluscs and polychaete worms, as well as organisms that play key roles in natural communities.

Development and morphology: While lophophorates retain their lophophore feeding structure, trochozoans are often associated with a trochophore larval stage in development; not all lineages retain these features, but molecular data consistently place them together within Lophotrochozoa. The group exhibits immense anatomical and physiological diversity, reflecting its long evolutionary history.