Phoronida—A small clade with a big role in understanding the evolution of lophophorates

Abstract

Phoronids, together with brachiopods and bryozoans, form the animal clade Lophophorata. Modern lophophorates are quite diverse—some can biomineralize while others are soft‐bodied, they could be either solitary or colonial, and they develop through various eccentric larval stages that undergo different types of metamorphoses. The diversity of this clade is further enriched by numerous extinct fossil lineages with their own distinct body plans and life histories. In this review, I discuss how data on phoronid development, genetics, and morphology can inform our understanding of lophophorate evolution. The actinotrocha larvae of phoronids is a well documented example of intercalation of the new larval body plan, which can be used to study how new life stages emerge in animals with biphasic life cycle. The genomic and embryonic data from phoronids, in concert with studies of the fossil lophophorates, allow the more precise reconstruction of the evolution of lophophorate biomineralization. Finally, the regenerative and asexual abilities of phoronids can shed new light on the evolution of coloniality in lophophorates. As evident from those examples, Phoronida occupies a central role in the discussion of the evolution of lophophorate body plans and life histories.

Old hypotheses and theories at the heart of current evo‐devo research

“…For example, the mysterious "shelly" fossilized hyoliths, which are abundant in the Burgess Shale, have been eventually asserted as Cambrian lophophorates after several decades of debate. Gąsiorowski (2023) brings us into the fascinating world of lophophorates through the lens of extinct and modern phoronid lineages. Because of their morphological diversity, phoronids can shed new insights into the origin of numerous metazoan traits, including larval stages, coloniality, biomineralization, and regeneration.…”