Metamorphic remodeling of morphology and the body cavity in Phoronopsis harmeri (Lophotrochozoa Phoronida): the evolution of the phoronid body plan and life cycle

摘要

BackgroundPhoronids undergo a remarkable metamorphosis, in which some parts of the larval body are consumed by the juvenile and the body plan completely changes. According to the only previous hypothesis concerning the evolution of the phoronid body plan, a hypothetical ancestor of phoronids inhabited a U-shaped burrow in soft sediment, where it drew the anterior and posterior parts of the body together and eventually fused them. In the current study, we investigated the metamorphosis of Phoronopsis harmeri with light, electron, and laser confocal microscopy.