The organisms which excrete nitrogen waste substances in form of ammonia.
Ammonia requires a large amount of water to dissolve.
Example- sepia, octopus, and bony fishes.
Bony fishes:
In bony fishes, ammonia is excretory material because it is a very toxic substance to tissues but extremely soluble in water.
Approximately 0.5 L of water is required per 1 g of nitrogen to keep ammonia levels in excretory fluid below the level in body fluids to avoid toxicity.
In aquatic animals, this mode of excretion is preferred. Ammonotelic excretion is the process by which ammonia is excreted.