My curiosity for fish scales began on our field trip to the Madison River. I could not help but admire the amazing scales that different fish possess.
Coming back, I decided to conduct research on fish scales. Here’s a brief synopsis of my analysis.
Understanding Fish Scales
Fish scales are composed of rigid, small plates that grow out of their skin. Their rough texture helps protect the marine life from predators, disease, and habitat infusion.
Fish scales vary in shapes and sizes: Some fish have round overlapping scales that help ensure smooth sailing with limited drag. Others have spiked outer edges and non-overlapping scales.
The fish’s lateral line is covered with pores within its scales to detect sounds and vibration, communicate, and locate prey.
Types of Scales
These are the four types of scales that the fish possess:
Cycloid and Ctenoid Scales
Cycloid and Ctenoid are the most common types of fish scales. They are made from bones and collagen, typically found on bony fish and other species.
Bearing similar characteristics, both types of scales can be classified in the same category. However, they differ in smoothness of their edges. The cycloid scale has a smooth edge, while the ctenoid scale has a spiny one.
Most fish have only one of these two, while some contain both. Some species of flatfishes have ctenoid scales on the eyed side of the body and cycloid scales on the blind side. They are common on fish with soft fin rays, such as salmon and carp.
Placoid Scales
Placoid scales are found in cartilaginous fish like sharks and rays. These scales are often referred to as denticles.
Placoid has a central pulp cavity of blood vessels surrounded by a layer of dentine or vitrodentine(a substance similar to enamel).
Most fish are covered in a layer of mucus or slime that protects against pathogens and reduces surface resistance when the fish swims.
Each placoid scale consists of rectangular plates embedded in various structures like spines. As the fish grows, so do the placoid scales. The spaces are aptly covered by them.
As seen through a microscope, modified placoid scales have similar composition like human teeth. They are found on the skin of sharks and other carnivores.
Cosmoid Scales
Cosmoid is the least common scales of all, found on lungfish and the extinct lobefin.
They consist of two basal layers of bone, a layer of dentine-like cosmine, and an outer layer of vitrodentine.
Not much is known about these scales or who wore them, but it is said that the cosmoid scales are derived from the placoid scales.
Ganoid Scales
Ganoid scales are found on bowfin, gar, sturgeon, and bichirs. They have a similar chemical composition like placoid scale; these scales are rhomboid-shaped with peg and socket joints.
Like placoid, these scales also resist attacks from different predators by providing an effective camouflage.
They grow in size with the fish, similar to those of bony fish. Ganoid scales are also known from some fossil paleoniscoid fish.
Variation In Scale Size
Diversity of fishes also offer numerous sizes of fish scales. Some fish, such as freshwater eels, tunas, and silvery have tiny embedded scales while coral snappers have medium-sized scales.
The scales on silvery fish act as effective reflectors to keep away predators. They become visible at night time.
Do all fishes have scales?
No. Many species of fish lack scales. Clingfishes, for example, are scaleless. Their bodies are protected by a thick layer of mucus that acts as a barrier to injury or parasites.
Most species of catfish are also scale-less. But they have a sharp, dorsal fin to assist in navigation and stability.
Do Fish Scales Increase in Size?
Yes, fish scales augment in size as the creature becomes an adult. The new growth rings called circuli, are formed around the scales. It helps determine the fish’s age and growth patterns.
Fun Facts
Fish scales contain collagen, a protein used for skin, joint, and anti-aging products.
Several cosmetic manufacturers use brilliant metallic scales to provide sheen and shimmer in their makeup. Scales tarpon, for example, is used to make jewelry.
According to recent research, collagen can also be used for bioactive peptides that offer numerous advantages.
Wrap Up
I hope you found my research helpful in learning about different kinds of fish scales, their role, and uses.
