If you have ever been to a fish market or caught your own fish, you will already know that most fish have scales, you know, those plastic flakes that cover their body that tend to make a mess and are soo difficult to remove. Why Do Fish Have Scales?
Fish scales act like armor protecting fish from scrapes on rocks & branches protecting the fish from injury, & shielding fish from predators. Scales provide defense against parasites. They make fish more aerodynamic & help them move through the water faster up, down, or sideways without changing speed.
The scales of a fish contain a variety of pigments that can give the fish different types of colors. The scales form rows along the lateral line of the fish and help in detecting vibrations in the water as it acts as sensory receptor.
Why Do Fish Have Scales
No. Many species of fish lack scales. Fish that do not have scales include catfish, sharks, rays, chimeras, skates, moray eels, sturgeons, paddlefishes, sailfin blennies, combtooth blennies, hagfishes, and lampreys. Many of these fish have evolved scale alternatives.
Scales are more than just fish skin and serve several purposes. depending on where the fish’s environment is, scales serve a purpose and developed over generations of the species of fish. Scales act almost like armor protecting the fish from predators, and scrapes on rocks and branches.
- To protect the fish from injury, and to shield the fish from predators.
- Scales provide defense against parasites.
- They make fish more aerodynamic and help them move through the water faster.
Scales allow easy movement up, down, or sideways without changing speed. Sharks will typically use their scales to help them quickly change direction by reducing drag. The arrangement of scales on the body of the fish can also help tell the age of that type of fish.
All fish have a slime coat secreted from under the scales. It also protects against infection and parasites. Some fish have a toxic slime layer, another defense against predators.
Fish sometimes lose their scales and usually do grow back. Fish that have sustained minor trauma, will grow their scales back fairly quickly. While the damaged area is unprotected, the fish is more vulnerable to disease, fungus, and parasites.
Different Types of Fish Scales
There are four main kinds of scales and numerous variations of each kind. Fish scale sizes vary greatly between species.
Placoid (sharks and rays)-Placoid scales are usually flattened rectangular shapes. They can be found on sharks and rays. These scales don’t change in size as the fish grows. New scales grow in to fill up the empty space.
Cosmid (lungfishes and some fossil fishes)-Cosmoid scales are very similar to placoid scales in shape and size. They are usually found on fossil fish as well as lungfish. These strong scales consist of two layers of bone, a layer of dentine, and a final layer of vitrodentine. This is not a scale that would be fun to bite down on.
Ganoid (bichirs, Bowfin, paddlefishes, gars, sturgeons)-Ganoid scales take on the shape of a rhomboid and articulating peg and socket joints in between them. These can be found on a wide variety of fish such as sturgeons, bowfin, and paddlefish just to name a few.
Cycloid and Ctenoid (most bony fishes)-The cycloid and ctenoid scales are the most common type of scales found on bony fish. These scales have greater flexibility than the other ones because the anterior part of the scale is overlapped with the posterior part of the scale in the front.
Some species of flatfish like flounders, soles, etc have Ctenoid scales on the eyed side of the fish’s body and Cycloid scales on the blind side.
The Benefits of Scales on Fish
Fish have two layers of skin.
- The epidermis, which is the outer layer, secretes mucus-like substances that protect the fish’s skin from bacteria and fungi.
- The dermis forms the inner layer of its skin and is made of tough bony material.
Rings on every scale can tell us about a fish’s age. Fish Scales act as a Protective barrier from things that would harm the health of the fish, like parasites and bacteria.
They also help the fish move through the water, escaping any dangers that can threaten the fish. The harder the scales are, the faster the fish can move through the water with less resistance adding more protection for the fish.
There are fish with softer and lighter scales that are able to be flexible and move faster because of less weight. Fish scales can also act as camouflage in its environment, protecting them from predators.
All fish have a slime coat secreted from under the scales. This slime coat keeps the fish moist. It also protects against infection and parasites. Some fish have a toxic slime layer, another defense against predators.
Why Don’t Deep-Sea Fish Scales Grow
Ocean fish can have scales. These scales can be opaque or transparent, as well as colorful. However, some ocean fish do not have scales. Distinct fish species have different sorts of scales. A fish’s scales are determined by its surroundings.
There are certain fish that lack scales. Based on their habitat, these fish have developed additional defenses against predators, parasites, and illness. Scaleless fish frequently have extensive slime layers or bony plates.
Even within the ocean, there is a significant variety of habitats. From lakes to mudflats to the ocean. That’s why fish appear so distinct from one another. Because ocean fish are of many types. Some have scales, while others do not. Fish have evolved over many years based on their environments.
Do Fish Scales Grow Back
Most fish do not shed their scales, unlike reptiles who shed their skin as they grow. Scales are more like human skin. Since they have a blood supply, fish scales will grow with the fish. There is an exception to this is the swordfish. Young swordfish have scales but shed them all before they reach adulthood.
Fish scales usually do grow back. Fish that have sustained minor trauma or infections from bacteria will grow their scales back fairly quickly. While the damaged area is unprotected, the fish is more vulnerable to disease, fungus, and parasites. New scale growth comes like human fingernails. The fish’s new scales tend to be smaller and light in color.
Removing Scales From Fish
Normally people that enjoy eating the skin of fish will often descale the fish before cooking it. The best way to remove scales from any fish is to boil them in water for a few minutes, then drain the water and rinse them with cold water.
You can also use a vegetable peeler to peel off the skin, but be careful not to use too much force, as it can damage delicate scales and make a mess.
You can also cook the fish first with the scales and skin still attached. After your fish is done, remove the skin. The fish skin will be loosened by the heat, and you can cut it off pretty easily. The scales will come off with the skin.
Can You Eat Fish Scales
Yes, fish scales are edible. That doesn’t mean you’re going to want to eat them though it’s more an acquired taste. Scales are made in the mesoderm. This means that the way scales grow is closer to bones or teeth than reptile scales. Fish skin is usually acceptable to consume as long as it has been well-washed and the exterior scales have been removed.
Kosher dietary laws prohibit the eating of fish without eating both scales and fins. People that eat salmon will often eat the fish with the skin on the fish that is rich in nutrients like omega 3. They are also known to have a healthy dosage of collagen in them, which is used especially in health foods, pharmaceuticals, and processing industries.
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