What are the types of scales in fish?

There are four main kinds of scales and numerous variations of each kind.

  • Placoid (sharks and rays)
  • Cosmoid (lungfishes and some fossil fishes)
  • Ganoid (bichirs , Bowfin, paddlefishes, gars, sturgeons)
  • Cycloid and Ctenoid (most bony fishes)

What is the most common fish scale?

The most common form of fish scale is the elasmoid scale. It is the thin plate that you find on most fishes. It is often described as coming in two forms: ‘Ctenoid’, which have a set of fine teeth along the posterior edge and ‘Cycloid’, which are simply rounded on the outer/posterior edge.

What are the difference between Ctenoid and Placoid scales?

Placoid scales are predominantly found in cartilaginous fish while ctenoid scales are more common in bony fish.

What is cycloid and Ctenoid scales?

Cycloid scales are large, thin, and round or oval in shape, and they exhibit growth rings. Ctenoid scales resemble cycloid scales but have comblike teeth on their overlapping edge.

What are Placoid scales?

Placoid scales are found in sharks and rays, and can vary greatly in external appearance. Unlike the scales of bony fishes, placoid scales do not increase in size as the fish grows, instead new scales are added between older scales. Placoid scales are often referred to as denticles.

What is the difference between Placoid and cycloid scales?

The key difference between placoid and cycloid scales is that placoid scales are triangular, rough structures present in cartilaginous fish, while cycloid scales are round, flexible structures present in bony fish. The exoskeletal covering of vertebrates is made of two types of scales. They are epidermal and dermal.

What is a Placoid scale?

What is Placoid and cycloid?

Placoid scales are triangular, rough structures present in cartilaginous fish, while cycloid scales are round, flexible structures present in bony fish. Thus, this is the key difference between placoid and cycloid scales.

Why fish have different scales?

Fish scales primarily serve two purposes: protection and locomotion. What distinguishes these various scales from each other is both their composition and how they balance those two functions. The more ancestral a scale, the better its configuration is for protection rather than locomotion (1).

What is difference between Placoid and cycloid scales?

What is cycloid scale?

Cycloid scales appear to be the inner layer of ganoid or cosmoid scales. Found in carps and similar fishes, they are thin, large, round or oval, and arranged in an overlapping pattern; growth rings are evident on the free edges.