Question

What are two structures other than skin and gills that fishes use for respiration, (+EC cite example taxa for each type and whether they are facultative or obligate “air breathers”)

Answer 1

Ans . The two structures other than skin and gills that fishes use for respiration are:-

i) Spiracle :- spiracles are breathing openings found on the surface of insects, certain cartilaginous fish such as certain species of shark , and sting ray. Shark is obligate air breather.The clade of shark is Selachimorpha and are sister group to the rays. The Spiracles open into the fish's mouth, where water is passed over its gills for gas exchange and out of the body.

ii) Operculum :- The operculum is a hard, plate-like bony fap that covers the gills of a bony fish (superclass: Osteichthyes).e.g. Tuna, sardines. Tuna is facultative air breather. It protects the gills and also serve a role in respiration.The clade of bony fish is Teleostomi. Fish can acquire dissolved oxygen through pumping water over their gills by opening and closing their jaws and opercula.