Question

Excretory organs in fishes are
(a) Malphigian tubules
(b) Nephridia
(c) Kidney
(d) Flame cell

Answer 1

They are one of the most important organs of the human body which looks like a pair of beans, located below the ribs on both sides of the spine. The kidney’s average height varies from species to species and thus differs in its efficiency.

Complete answer
Kidneys are the main organs of the human excretory system. Every individual has a pair of
Kidneys. It is the excretory organs in the case of fishes. Fishes are ammonotelic i.e they secrete ammonia as the main excretory product. During the process of nucleic acid and protein synthesis, various types of nitrogenous waste substances are produced that include urea, uric acid, and ammonia, based on the habitat of various organisms. Ammonia is found to be the most toxic nitrogenous wastes and is needed to be removed as quickly from the body as possible. For its removal first, it has to dilute by the use of excessive water.
The kidneys of the fishes are adaptive in order to maintain their water balance such that teh urine which is secreted must be diluted in nature. The kidneys just like humans constitute a large glomerulus along with numerous capillaries which will help the blood in the filtration process and resulting in the production of the urine.
Through the mouth and the gills, the water also enters their body continuously. Due to the process of diffusion, the salts will be lost from the body. The special gills then help in the transportation of salt into the body from the salty water bodies surrounding them which results in the maintenance of the osmoregulation. This absorption of salts and their transportation through gills need a high amount of energy which is fulfilled through the presence of mitochondria-rich cells.

So, the correct answer is ‘Kidney’.

Note:
The excretory system present in the cockroaches is the malpighian tubules which consist of a branched network. Special excretory organs called nephridia excrete the nitrogenous waste out of the body in the case of the earthworms. Nephridia are the special excretory organs that help in the excretion of the nitrogenous waste out of the body.