Question

Trimethylamine is the excretory product in
(a) Freshwater fishes
(b) Molluscs
(c) Amphibians
(d) Marine teleosts

Answer 1

Hint: It is present in the members of the ray finned fishes which produces trimethylene from the ammonia to excrete outside the body. These organisms are present deep inside the oceans, estuaries, rivers, lakes, etc.

Complete answer:
Trimethylene is the colorless organic compound that is the excretory product of marine teleosts and maybe certain molluscs along with crustaceans. Trimethylamine is produced from the ammonia and methanol that are catalyzed by an enzyme.
- Trimethylamine is a tertiary amine which is flammable and is gaseous at room temperature.
- It smells like ammonia but at a lower temperature, it smells like the rotten fish.
- The specific character of marine teleosts is the movement in their jaws which helps them to grind and swallow their food.
- Their caudal fins have equal size both on the upper and the lower lobes.
- They acquire a variety of reproductive processes including external fertilization, internal fertilization, and even a few teleosts are hermaphrodites.
- They are important in the fishing industry where they are harvested to produce food for fishes.
- They are used widely in research mostly in the field of genetics and developmental biology.
- The trimethylamine is tested by the gas sensors to find out the freshness of the fish.

So, the correct answer is ‘Marine teleosts’.

Note: In 1844 the German ichthyologist Johannes Peter Muller was the first to recognize a different group of species. The word teleosts is derived from the Greek word teleios, meaning ‘complete’ and osteon, meaning bone. They were classified on the basis of their characters of soft tissue but the features of fossil teleost were not taken into account. The clearer and more accepted classification was provided in 1966 by Greenwood et al. In the Early Triassic period, the first fossil of this group appeared.