How Ammonotelism Differs from Ureotelism and Uricotelism
Animals excrete nitrogenous waste in many forms. In this article, we shall examine ammonotelic organisms.
The process of excreting nitrogenous waste within the sort of ammonia is termed ammonotelic. The phenomena is recognized as Ammonotelism.
Most aquatic animals like Birds, amphibians, reptiles including fishes, some terrestrial invertebrates, larvae, and mammals including humans excrete urea acid as waste.
Ammonia, which is very water-soluble and which forms ammonia water (NH4 OH) directly injures cells by the alkaline caustic action. Therefore, the excretion of ammonia requires large amounts of acid . Some part of the uric acid is oxidized furthermore to form allantoic acid and allantoin.
Note: Allantoate or hydration product of allantoin is excreted by theTeleost fish. Allantoate is hydrolyzed into glyoxylate and urea in most amphibians and fishes. Creatine is made within the liver from amino acids. The resultant creatinine is generated from creatine.
Excretion
Almost all animals possess a particular mechanism of getting rid of the waste substances formed in their body during metabolic activities. Carbon dioxide, water, urea, uric acid, ammonia, etc. are some of the waste substances that could be harmful if they remain in the body. Besides metabolic wastes, excess salt (eg. Sodium from food), water and even certain excess vitamins got to be eliminated. Certain medicines, including antibiotics are faraway from the blood into the urine.
Excretion can be defined as the removal of all harmful, unwanted products (especially nitrogenous wastes) from the body. The excretory system is majorly associated with the removal of wastes that are nitrogenous. Urea is regarded as the primary nitrogenous waste produced in our body. It is made by the breakdown of surplus amino acids and nucleic acids in the liver. Blood transports urea to the kidneys for filtration and removal within the sort of urine.
Importance of Excretion
Excretion is important for the elimination of nitrogenous wastes formed during the metabolism of proteins (amino acids) and nucleic acids.
For elimination of excess salts like common salt (NaCl), vitamins, bile pigments (from the breakdown of old RBCs)
The removal of excess water or its retention just in case of shortage. This helps to take care of the specified quantity of water – osmoregulation within the body.
Importance of Osmoregulators and Osmocomformers
Osmoregulation may be a process that regulates the pressure of fluids and electrolyte balance in organisms. In animals, this process is caused by osmoreceptors, which may detect changes in pressure. Humans and most other warm-blooded organisms have osmoreceptors within the hypothalamus. Besides the brain, osmoregulators also are found within the kidneys.
Different organisms exhibit different types of osmoregulation. Fish, Bacteria, Plants, Animals and even Humans undergo osmoregulation processes.
There are Two Types of Osmoregulation, Namely
Osmoconformers and
Osmoregulators.
Osmoconformers can be defined as the organisms that attempt to match the osmolarity of their body with their surroundings. In other words, these organisms maintain an equivalent pressure inside the body as outside water. They conform either through active or passive means. Most marine invertebrates like starfish, jellyfish and lobsters are osmoconformers.
Osmoregulators are a kind of organisms that actively regulate their pressure , independent of the encompassing environment. Many vertebrates, including humans, are osmoregulatory. Most seafood are considered to be osmoregulatory too.
FAQs on Ammonotelism Explained: Definition, Importance & Examples
1. What is ammonotelism as explained in Class 11 Biology?
Ammonotelism is a mode of excretion where the primary nitrogenous waste product eliminated from the body is ammonia (NH₃). This process is characteristic of organisms that live in aquatic environments, as ammonia is highly toxic and requires a large amount of water for dilution and removal. As per the CBSE syllabus, it is one of the three major types of nitrogenous waste removal strategies in animals.
2. Which types of animals are considered ammonotelic? Provide some examples.
Ammonotelic animals are typically those with constant access to water. Examples include:
- Most bony fishes: They excrete ammonia directly into the surrounding water through their gills.
- Aquatic amphibians: For instance, the tadpole stage of a frog is ammonotelic.
- Aquatic invertebrates: Many invertebrates living in water, such as protozoans and crustaceans, excrete ammonia across their body surface.
3. How does ammonotelism differ from ureotelism and uricotelism?
The key difference lies in the type of nitrogenous waste, its toxicity, and the amount of water required for its excretion. Ammonotelism involves excreting highly toxic ammonia, which needs lots of water. Ureotelism (seen in mammals, terrestrial amphibians) involves excreting less toxic urea, requiring a moderate amount of water. Uricotelism (seen in birds, reptiles) involves excreting uric acid, which is the least toxic and requires very little water, often being passed as a semi-solid paste.
4. Why is ammonia considered a dangerous excretory product for terrestrial animals?
Ammonia is extremely toxic to cells and can raise the pH of body fluids to dangerous levels. To be safely removed, it must be diluted with a large volume of water. Terrestrial animals, which need to conserve water, cannot afford to lose such large amounts. Therefore, they convert ammonia into less toxic substances like urea or uric acid, which can be stored temporarily and excreted with minimal water loss.
5. What is the primary advantage of ammonotelism for an aquatic organism?
The main advantage of ammonotelism is energy conservation. The conversion of ammonia into urea (in the urea cycle) or uric acid is an energy-intensive metabolic process that requires ATP. By excreting ammonia directly, aquatic animals save this metabolic energy. Furthermore, ammonia is highly soluble and can easily diffuse across body surfaces like gills, making its removal a relatively simple process.
6. How is ammonia produced in an animal's body before being excreted?
Ammonia is primarily produced through a process called deamination. During the metabolism of proteins, excess amino acids are broken down. The amino group (-NH₂) is removed from the amino acid, forming ammonia. This process mainly occurs in the liver. While all vertebrates produce ammonia this way, only ammonotelic animals excrete it directly without conversion.
7. How is ammonotelism linked to the process of osmoregulation in freshwater fish?
In freshwater fish, ammonotelism and osmoregulation are closely linked. These fish live in a hypotonic environment, meaning water constantly enters their bodies. To maintain their internal salt-water balance (osmoregulation), they must excrete this excess water. They do this by producing large volumes of very dilute urine. Excreting highly soluble ammonia as their nitrogenous waste is efficient because it can be easily flushed out with this excess water, simultaneously solving the problems of waste removal and water balance.
