Practice question

Phoronida comprise small exclusively marine vermiform coelomate phylum commonly called horseshoe worms because lophophore typically forms horseshoe-shaped crown of hollow tentacles encircling mouth, especially in Phoronis ovalis though other species show spiral coil with many tentacles. Body differentiated into minute prosome, mesosome bearing lophophore, elongate metasome enclosed in self-secreted tubiculous chitinous tube often impregnated with sand, attached to hard substrate. Feed via ciliary downstream collection, possess U-shaped gut, closed circulation with hemoglobin, actinotrocha larva pelagic. Horseshoe epithet describes tentacular disposition, not overall worm shape, indicating feeding geometry adapted for sessile suspension feeding.