Question

What types of scale present on cartilaginous fishes?

Answer 1

• Placoid scales are present on cartilaginous fishes and are hard and microscopic in size. Their body is made of dentine and the exposed surface is covered with a layer of hard enamel.
• There is a pulp cavity in which dermal papilla sits during the development of the scale. In structure, placoid scales resemble a tooth and for the same reason, the teeth of sharks are modified placoid scales that are anchored in the dermis and are replaced throughout life.