Practice question

Nematodes possess unique single-celled excretory apparatus unlike coelomate nephridia. Primitive Adenophorea possess single ventral glandular renette cell opening via anterior pore, secreting ammonia. Derived Secernentea display H-shaped system formed by fusion of two renette cells into tube with two lateral canals embedded in lateral hypodermal chords, connected by transverse canal and terminal ampulla opening ventrally. Lumen lined by cuticle. Removes waste, regulates ions. Distinguishes Nematoda from annelid metanephridia, platyhelminth protonephridia, crustacean green glands and molluscan kidneys, highlighting pseudocoelomate evolutionary divergence and physiological adaptation to cuticle-enclosed high-pressure body plan and soil habitat.