Question

Air bladder occurs in:
(a) Torpedo
(b) Scoliodon
(c) Anabas
(d) Elasmobranch

Answer 1

Hint:This species is also called climbing perch as well as walking Fish, which is a small Asian freshwater fish of the order Perciformes. It is named so because of their ability to live and walk about out of water. This fish is an air-breathing labyrinth fish. It grows to about 25 cm (10 inches) rather oblong, brownish, or green in color. It basically lives in ponds and ditches but sometimes it is seen for short periods, “walking” with a jerky motion.

Complete step by step answer:
Many bony fishes possess the swim bladder or air bladder which is a buoyancy organ and is located in the body cavity and is derived from an out pocketing of the digestive tube. This air bladder contains gas (usually oxygen) and functions as a hydrostatic or ballast organ, which helps the fish to maintain its depth without floating upward or sinking. To produce or receive sound, this swim bladder serves as a resonating chamber. The swim bladder contains oil instead of gas in some species. It functions as a lung or respiratory aid instead of a hydrostatic organ in certain species but is missing in some bottom-dwelling and deep-sea bony fish (teleosts) and all cartilaginous fish (sharks, skates, and rays).

So, the correct answer is, ‘Anabus’.

Additional information:
1) The cartilaginous fish like sharks and rays do not possess swim bladders. Some of them use a dynamic lift to control their depth only by swimming; while others which do not change with depth store fats or oils with a density less than that of seawater which is used to produce a neutral or near-neutral buoyancy.
2) In aquarium fishes, swim bladder disease is commonly seen where the diseased fish can float nose down tail up or can float to the top or sink to the bottom of the aquarium.
3) It is also seen that swim bladders are used in the food industry as a source of collagen where they can be made into a strong, water-resistant glue, or used to make isinglass for the clarification of beer.
4) A strong reflection of sound is produced by the gas/tissue interface at the swim bladder which is used in sonar equipment to find fish.

Note: The jellyfish-like colonies have a special swim bladder called siphonophores that allow them to float along the surface of the water while their tentacles trail below. Farmer proposed in 1997 that lungs evolved to supply the heart with oxygen. Blood circulates from the gills to the skeletal muscle, and only then to the heart in fishes. An advantage given by the primitive lungs is that it supplies the heart with oxygenated blood via the cardiac shunt. Fossil record supported this theory robustly, the ecology of extant air-breathing fishes, and the physiology of extant fishes.