What is a fish?

In this article, we will concisely define fish and its benefits, so stay tuned to the Farmidarena site until the end of this context.
Most of us have probably seen that marine animal, but how much do we know about this useful creatures?
That is an aquatic vertebrate that needs gills and fins to swim.

All fish have two property in common: They can only live in water and have a spine (they are vertebrates).
These beautiful creatures reproduce by spawning , live in hot and cold waters, deep oceans and even rivers.

Fish History:

Historically, the first vertebrates that formed about 480 million years ago were fish.
About 320 million years ago, when the golden age of that began and aquatic animals were the best and most advanced living organisms in the world, the density and expansion of that was at its peak.

The first fish to emerge were the Jawless fish, whose fossils are found in sediments in Devine, a coastal area in England.
Later in the same period, the first jawed fish, which are actually the main ancestors of modern sharks, emerged.
In the late Devonian period, bony fish appeared.
Today this animals are the result of evolutionary changes.

Physical structure

The appearance of this marine animal is spindle and if we make a cross section in it, we will see it in an oval shape. Some of these creatures can be round, wide, striped, thread-like, snake-like, and so on. In addition have a hardcover that protects all parts of their body.

Even their eye sockets are protected by this cover and have a light color.
The skin, muscles, organs of fish are protected by scales.
The size of the scales can be as small as a microscope or the size of a coin. The scales are placed around the body of the its in a circle. This useful animal can be colorless or colored.

Physical features

They have common characteristics that distinguish them from other animals and include the following

• Fish are cold-blooded

All fish are warm-blooded or cold-blooded;
That is, they can not regulate their internal body temperature.
Even warm-blooded fish such as tuna and sharks
It only has local warmth, which means that the warmth in their body is limited to certain areas.

• Have aquatic habitat

The fish are amazingly diverse.
These creatures include more than 33,000 species of vertebrate animals that live in the fresh and salty waters of the world,
and some scientists believe that there are about 40,000 species of fish in the world, of which more than 10,000 species have not yet been identified.
This large family is not the only creature that lives in the water. It is good to know that other animals such as snakes, dolphins, shrimp, oysters, etc. also live in the water.

• Have gills to breathe Fish have gills throughout their lives. All them have gills ,But not all creatures have gills, are not fish.(Such as immature groups of amphibians)

• Have swimming bladders (floating bags) for swimming .These specialized organs are filled with air to keep the fish afloat, and in some species they help them survive at low oxygen levels. They also help fish sleep and detect the movement of food and predators.
• They have fins for moving

The most common fish fins include the caudal fin, a pair of lateral fins, a dorsal fin and an anal fin.
There is a lot of variety in the fins and their shapes, but they all provide movement, and stability.

Benefits of fish

Rich in vitamins

Fish have always been considered because of their high nutritional value in the human diet.
Due to the variety and large number of fish, in the past it was thought that no matter how much these creatures were caught, it would not cause any problems.
But today it is clear that over fishing can cause irreparable dangers to the ecosystem.

Beauty

Many people keep ornamental fish in aquariums for their beauty.
This has created a job called ornamental fish farming.
Some people go fishing by the river for fun.