This is a paired gland in the head region of the crustacean. These organs are capable of filtration, reabsorption, and secretion. D. Malpighian Tubules Used by insects. Does not seem to involve any ultrafiltration in the urine formation process. Instead, they use secretion as the primary mechanism of waste product removal.
Reabsorption can take place as well, however.
E. Kidneys First seen in molluscs, but best developed in the vertebrates. Almost all kidneys are capable of filtration, reabsorption, and secretion. The nephron is the functional unit of the kidney. There are about 1 million nephrons within the kidney. Collecting duct Blood supply to the kidney 1.