All living organisms consume nutrients that are required for the production of both tissue and energy. The waste products of this process include nitrogenous materials and inorganic salts. They are removed from the body by excretory organs, which in vertebrates have developed into kidneys and into salt glands in some birds and reptiles. Many invertebrates use a series of excretory organs called nephridia to perform the same function. As an example, the nephridia of the giant Gippsland earthworm (Megascolides australis) contain a ciliated funnel that opens into the coelomic cavity and connects to a tubule, which opens to the exterior of the body by a nephridiopore . Coelomic fluid enters the tubule, water and important nutrients are absorbed through the wall, and dilute urine containing urea and ammonia is excreted from the tubule. Insects have a similar arrangement except that the tubules connect to the hindgut instead of the exterior. Body fluids are drawn from the coelom into these by osmosis following active secretion of sodium, potassium, and uric acid inside the tubule. Water is reabsorbed from the hindgut, and nitrogenous waste, mostly uric acid, is expelled in relatively dry feces.
|Number of pages||11|
|Journal||Veterinary Clinics of North America - Exotic Animal Practice|
|Publication status||Published - 2006|