Practice question

Excretory apparatus in Hemichordata centers on glomerulus or proboscis gland, a vascular knot of blood vessels projecting into protocoel anterior to stomochord, filtering hemolymph through podocytes to produce urine collected via protocoel pore. Additionally, gill slit region contributes to excretion via branchial epithelium diffusion. Among simplified textbook choices, gill slits region is historically linked to excretory function because filtrate drains near pharyngeal area and wastes diffuse across gill surfaces. Unlike segmented nephridia of annelids, intracellular flame cells of flatworms or Malpighian tubules of insects, hemichordate ultrafiltration via glomerulus illustrates primitive deuterostome arrangement.