AMMONOTELISM

Humans and other animals excrete or release wastes outside the body in the form of urea or feces. Some organisms excrete their wastes in various forms. Some may excrete as ammonia, amino acids etc. Excretion is important for every living organism in the world as it helps to release the unwanted substances(salts, metabolic wastes, water, and ammonia) present inside the body.

Have we wondered how fishes or other organisms excrete their wastes as they are aquatic(water-living organisms)? Nitrogenous wastes can be excreted in many forms. Here we will discuss one of the forms of nitrogenous waste excretion.

Excretion And Its Importance

Excretion is the process of eliminating unwanted substances(especially nitrogenous wastes) from the body. It is done by the excretory system. Wastes are generated by metabolic activities done by the body. Wastes are ammonia, water, excess salt, uric acid, and carbon dioxide. Some of the wastes can harm the body if not removed. Excretion eliminates these wastes. Nitrogenous waste in the human body is urea. Extra nucleic acids and amino acids are broken by the liver. Urea is transported by the blood to the kidney. Kidney filters and waste is eliminated as urine.

Excretion Importance

• It helps in the regulation of pressure in fluids(osmoregulation) by the release of excess water.

• It helps in the removal of nitrogenous wastes(amino acids, ammonia) and salts.

Modes Of Excretion

There are five modes of excretion based on the product excreted.

• Ammonotelism-ammonia(highly harmful) excretion
• Uricotelism-uric acid excretion
• Aminotelism-amino acid excretion
• Ureotelism-urea excretion
• Guanotelism-guanine excretion

What Is Ammonotelism

• Ammonotelism is the process of excretion of nitrogenous waste in the form of ammonia(formed by nitrogen and hydrogen).

• The organisms that excrete waste by ammonotelism are called ammonotelics.

• The excretion product ammonia is highly toxic and produces ammonium hydroxide with water(injures cells) and is highly soluble in water. it must be eliminated from the body once it is formed.

• Since ammonia can damage cells by alkaline reaction, excretion of ammonia needs a large quantity of water.

• In some invertebrates(organisms that lack vertebral columns) urea is hydrolyzed(oxidation reaction) to carbon dioxide and ammonia.

• In fish and other amphibians, allenoate(salt or ester of allenoic acid) is turned into urea and glyoxylate.

Excretion Of Ammonia

• When the organism's surrounding has a low ammonia level and the organism has a high ammonia level, then through passive diffusion(diffusion of molecules from a higher concentration region to a lower concentration region through the membrane) ammonia gets released into the surrounding.

• This nitrogen excretion mechanism is not adoptable for animals that live in high ammonia water. echinoderms, Platyhelminthes excrete ammonia by direct diffusion(skin).

• Aquatic fish excretes mostly through gills.

• The excretion of ammonia needs the least energy.

Examples Of Ammonotelism

All ammonotelics are aquatic animals

Examples are

• Larvae of amphibian

• Fishes

• Protozoans

• Cephalopods

• Echinoderms

• Platyhelminthes