Practice question

Crustacean excretory organs are antennal or green glands situated within cephalothorax at base of second antennae, named for greenish pigmentation. Each comprises end sac where hemolymph filters across coelomosac forming primary urine, labyrinth for selective reabsorption and secretion adjusting salt balance in marine versus freshwater habitats, and bladder storing excreta before discharge via nephropore on antenna. Ammonia excretion diffuses also across gills. Arachnids use coxal glands and Malpighian tubules, insects Malpighian tubules, myriapods Malpighian tubules. Antennal gland structure parallels vertebrate nephron functional analogy but anatomically distinct as crustacean diagnostic.