Question

Excretory material of bony fishes is?

• A. Urea
• B. Uric acid
• C. Ammonia
• D. Ammonium chloride

Hint:

Nearly all teleost (bony) fishes are ammonotelic, utilizing their gills as the major excretory organ for rapid ammonia clearance.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Nitrogenous waste excretion is an essential physiological process in vertebrates.
Aquatic animals, such as bony fishes (teleosts), live in environments with high water availability, which dictates their chosen mode of excretion.

Step 2: Detailed Explanation:
Bony fishes are primarily ammonotelic, meaning their primary nitrogenous excretory waste is ammonia (\(\text{NH}_3\)).
Ammonia is a highly toxic substance that requires large volumes of water to dilute it safely, which is easily achieved in aquatic habitats.
It is excreted passively as unionized ammonia (\(\text{NH}_3\)) and ammonium ions (\(\text{NH}_4^+\)) across the highly permeable gill epithelia.
Elasmobranchs (sharks and rays) primarily excrete urea (ureotelic), while birds and terrestrial reptiles excrete uric acid (uricotelic).

Step 3: Final Answer:
Hence, ammonia is the primary nitrogenous excretory product of bony fishes.