Practice question

Spatial relationship between anus and lophophore provides critical diagnostic criterion for segregating Entoprocta from Ectoprocta and other lophophorates. In true lophophorates Phoronida, Brachiopoda and Bryozoa termed Ectoprocta, tract U-shaped with anal opening located outside tentacular ring, dorsal to mouth, preventing fecal contamination of feeding current. Entoprocta previously grouped within Bryozoa possess anus inside tentacular circlet inspiring name inside anus. This distinction implies true lophophorates exhibit ectoproctous condition, anus external, key morphological synapomorphy debated in lophotrochozoan phylogeny and superphylum placement among spiralians and related phyla historically confused in classification.