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Question
Which type of scales are found on skin of cartilaginous fishes?
Which type of scales are found on skin of cartilaginous fishes?
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Solution
The correct option is D Placoid
Cartilaginous fishes (like sharks and rays) are covered with placoid scales.
Most bony fishes are covered with the cycloid scales of salmon and carp, or the ctenoid scales of perch, or the gonoid scales of sturgeons and gars.
Placoid scales are structurally homologous with vertebrate teeth having a central pulp cavity supplied with blood vessels, surrounded by a conical layer of dentine, all of which sits on top of a rectangular basal plate that rests on the dermis.
Thus, the correct answer is option (D), 'Placoid'.
Cartilaginous fishes (like sharks and rays) are covered with placoid scales.
Most bony fishes are covered with the cycloid scales of salmon and carp, or the ctenoid scales of perch, or the gonoid scales of sturgeons and gars.
Placoid scales are structurally homologous with vertebrate teeth having a central pulp cavity supplied with blood vessels, surrounded by a conical layer of dentine, all of which sits on top of a rectangular basal plate that rests on the dermis.
Thus, the correct answer is option (D), 'Placoid'.
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