Question

In which fish placoid scales are present?

Answer 1

Cartilaginous fishes:

1. They all are marine fishes.
2. Their endoskeleton is cartilaginous.
3. They have two pairs of fins with cartilaginous fins rays.
4. Their skin is rough, tough, and has minute placoid scales.
5. This group of fish is included in the class Chondrichthyes.
6. Examples of cartilaginous fishes include sharks, rays, skates, etc.

Placoid scales:

1. These are tridentate scales that are a part of cartilaginous fishes.
2. These are derived from the dermis of the skin.
3. The scale consists of an outer enamel layer, an inner dentin layer, and a pulp cavity.
4. Their presence makes the shark's skin rough.