Best 6 Types of Fish Scales

Types of Fish Scales – Assuming that fish represent one of the most diverse and interesting groups of animals in the animal kingdom, one of the most distinctive factors in the group is the factor of scales.

Scales perform a variety of functions; they protect the fish in case of injuries, parasites, and predators; reduce any friction in the movement of the fish in water, and also facilitate breathing and attract senses to some particular species.

Such research into fish scales is known as lepidology, and scales are also offered in a wide variety, all being adapted to the kind of life and environment of the fish that has them.

Overview of Fish Scales

Rigid, small plates that begin to form in the inner part of the skin, the dermis, but are covered by a thin layer of the epidermis, are called scales.

They are primarily made of bone, which is mainly found in most of them, except for the dentine or keratin in the case of fish.

Not all fish are scaled, but a few, like the catfish, have none, and some species, such as a few eels, still have small scales between them, giving the skin the appearance of smoothness and oilyness.

The scales of the fish also grow with the fish and, in most cases, assume the form of patterns or rings that can even be utilised to know the age of the fish, just like tree rings.

There are very loosely two general types of fish scales by way of evolutionary evolution placed in the first category of placoid (cartilaginous fish scales) and in the second category of bony fish scales (cycloid, ctenoid, ganoid, and cosmoid scales).

1. Placoid Scales (Cartilaginous Scales)

The sharks, rays, and skates (cartilaginous) fish occur.

Form: Tooth-form is the placoid scales (also called dermal denticles) of the tooth.

Each scale has the base of the scale as one of the low parts that press into the skin and the spine or cusp, which bulges in the opposite direction.

They include the inner pulp cavity, intermediate dentine, and outer resembling an enamel that is known as vitrodentine.

Function and Adaptation:

The scales deposited over the placoid bring out a hard armour that reduces the drag and turbulence, allowing the sharks and rays to navigate well in the water.

They are also able to survive the predators and parasitic creatures as a result of their sandpaper-like surface, which is rough. Surprisingly enough, the design of the placoid scales was utilised to ensure that modern swimsuits and underwater vehicles are more functional as far as the hydrodynamic characteristics are concerned.

An example of this is: Scales of a shark are placed so that by keeping a shark in a head-tail manner, you feel the roughness, and in an opposite head-to-tail manner, the smoothness.

2. Ganoid Scales

Location: Gars, bichirs (Polypterus), and sturgeons are primitive bony fishes.

Location

Form: Ganoid scales are diamond-shaped scales and are inclined to interlock with each other in the form of a mosaic.

They have a bony bottom and a dentine layer and a shiny outside layer that is made of ganoine, which is a substance similar to enamel and causes the scales to be glossy and resemble a suit of armour.

Function and Adaptation:

The scales are very resistant to predators due to their hardness, which makes them less able to bend. Ganoid scales are also typical of those fish that are slow-moving but ambling, and have armoured lives.

Like the gar fish with its thick glittering scales, it is an example of the gonoid type. Such scales are tough to the point of being used as jewellery and arrowheads by the locals.

3. Cycloid Scales

Occurrence: they occur in soft-rayed bony fishes, e.g., salmon, carp, and minnows.

Form Cycloid scales are thin, circular, and smooth-edged. These are the bones and lack the enamel and dentine layers. This is done by fitting these scales in intersecting structures, like tiling the roofs, hence their flexibility and ease of movement.

Function and Adaptation:

The cycloid scales can travel successfully because they can overlap, their texture is flattened, and there is not much resistance. Patterns of forced ring growth of these scales may also prove handy in the determination of the age and the rate of growth of the fish.

An instance: The scales of fish animals like the common carp, and the salmon are cycloid in character, and this nature of scaling also gives them an easy time in still water and in running water in the streams.

4. Cosmoid Scales (Extinct Type)

Localization: Extinct lobe-finned fishes and early lungfishes exhibit the localization.

Form: Cosmoid scales are thick and compact since they possess several layers, the inner one a bone layer, the middle one a dentine (cosmine) layer, and the outer enamel-like part.

Function and Adaptation:

Such scales provided a high degree of protection, but were hard and consequently did not instill much versatility, and as such, could not move quickly.

As the evolution has taken its course, these have been replaced by other, less massive forms of scales, which were more flexible as the fish adapted to different aquatic habitats.

Examples: Cosmoid scales are also demonstrated by vestigial signs in modern lungfish to have an ancient origin.

5. Scale evolution: significance of Morphology and Ghosts in fish scales.

To a great extent, the formation of fish scales occurs after the formation of vertebrates.

The original fish gained bony and heavy scales to defend themselves, though, in the process of evolution of predation and prey, the need to be quick and agile led to the emergence of light and thin scales.

Such an example of a gradual compromise between protection and movement is this non-opposable evolutionary pattern – cosmoid to ganoid to cycloid to ctenoid scales.

They are also used as scales in other aspects, such as defence, though they are also used in osmotic regulation, camouflage, and species identification. Its effects include selective breeding, changing the scale patterns in some species to form ornaments, e.g., the mirror carp.

Conclusion

Types of Fish Scales – Excellent biological examples of adaptation and diversity are fish scales. One of them has a kind: placoid, ganoid, cycloid, ctenoid, and cosmoid that reflects the forces of evolution and environmental context that informed the evolution of each form.

Scales are a rebellion against defensive colouring, an armour as hard as ganoid scales or as smooth as ctenoid ones, scales are an aegis, an opening and a passage to survival in the underwater environment.

The examination of these scales is not just a study of the fish anatomy/evolution, but also is an educational experience that has continued to bring additional technology in science, engineering, and design.

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