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Q.
Which of the following is not a character of bony fishes?
NTA AbhyasNTA Abhyas 2020
Solution:
Class osteichthyes is one of the classes of subphylum vertebrata of the phylum chordata. Adult fishes of this class have a bony endoskeleton, hence they are named bony fishes. The exoskeleton in bony fishes, if present comprises smooth scales, which are dermal in origin. These scales may be ganoid, cycloid or ctenoid. Pelvic fins in bony fishes don’t bear claspers. Claspers are the structures formed by the posterior portion of pelvic fins in the male cartilaginous fishes. Claspers serve to channel semen into the female’s cloaca during copulation. Bony fishes have 4 pairs of gills that are covered by an operculum on each side that helps them breathe without having to swim. The presence of air bladder is also an advantage, as it regulates buoyancy. The heart is 2 chambered (one auricle and ventricle each). They are cold-blooded. Ammonia is the primary nitrogenous waste. Sexes are separate. Fertilization is generally external and development is direct. They are mostly oviparous. They may be marine (Exocoetus), freshwater (Catla) or aquarial (Betta).