Did you know? The first vertebrates to emerge were fish, as these aquatic friends are believed to have inhabited the ocean for some 400 million years. In which we can find a lot of diversity due to its breadth, in this article we will explain the characteristics of the fish and more.
all about the fish
research on fish It can be a very attractive task, these aquatic animals have spent millions of years inhabiting the land. It turns out that they belong to the group of vertebrates, being the first to originate in said group. They are normally cold-blooded and breathe through gills. Its habitat can be in salt water or fresh water such as rivers and lakes, estimating that today there are more than 20.000 species.
These animals are very relevant in the daily life of man, since they are usually consumed. So they are a food source with high demand for human consumption, as well as being rich in nutrients and proteins that are beneficial for people's diets. That is why the fishing industry has specialized in the capture and reproduction of these fish to make it easier for people to consume them.
In addition to being a great source of protein and nutrients for the human diet, among one of the many fish characteristics, is the practice of rod fishing, which has been considered a world sport. When this activity is put into practice, it is capable of bringing together large groups of fans.
As well as we can find people who prefer to have these aquatic animals as a pet for the home, whether in fish tanks or aquariums to adapt them to a healthy life in captivity.
What are the characteristics of fish?
There is diversity of fish scattered in the ocean around the world. Many species that are ancient, others recently discovered and possibly several that are yet to be known. Currently, those that are present vary in size, shape, color, type of water, and highlighting some more than others.
Of the fish characteristics general can be mentioned:
- They have an internal skeleton.
- They do not have visible sexual organs.
- His eyes do not have eyelids.
- They cannot regulate their body temperature without the help of an external medium.
- They lack upper limbs, their movement is through fins with a variety of functions.
- In general, these aquatic animals have skin covered with scales, although there are some exceptions.
- Fish are part of animals that breathe through gills, however, only a very small group has pulmonary respiration.
- They have a terminal mouth, that is, these fish can be both carnivorous and herbivorous, as well as feed on others that are above or below them.
- In most of these fish, the body is larger than the head, which is made up of various articulated dermal bones. Whose function is to support your denture since it has no replacement.
- Their visual capacity is very high, as are their sensory organs, which allow them to detect vibrations or the proximity of enemies. Quite the opposite of what happens with their sense of smell, which is not very developed.
How are fish born?
The reproduction of the fish is diverse, since most of these aquatics carry both sexes. A large part of these species prefer to procreate in temperate or warm waters, since these can activate their sense of reproduction, making both females and males look for each other and unite. There are 3 kinds of fish:
- The viviparous they are the ones that have a unique way of feeding the embryo either by ovarian secretions or by placentation.
- The oviparous they are the ones that expel their eggs into the natural environment by burying them, or are even capable of carrying them in their mouths as a way of protecting their eggs, their fertilization is external.
- The ovoviviparous these retain the eggs inside the mother being expelled from her at the time of hatching, to protect their young from any danger or predator.
Its subsequent growth and development occurs according to the natural conditions of the environment, taking into account the temperature. Some fish have the ability to develop faster than others, reaching their adult stage without any delimitation, and in some cases being able to reach large sizes.
How are the fish according to their group?
fish characteristics vary according to the group to which they belong, these are divided into two:
agnathous fish
It is a very old group of fish, which is mainly characterized by not having a jaw or scales. Although these aquatic animals do not have vertebrae, they are still considered vertebrates, due to the factions of their heads and embryonic development.
This group also includes hagfish and lampreys, they can be distinguished by having an eel-shaped body, that is, with an elongated shape. They do not have fins, they are attached to other fish and do not suffer internal ossification, this is a process by which bone is formed.
gnathostome fish
This group includes the rest of the fish, in addition to including the Vertebrate animals of today, these would be amphibians, reptiles, birds and mammals. Between the fish characteristics They are gnathostomes, which have jaws and paired and unpaired fins. Likewise, they are classified into two types of fish:
chondrichthyans
These fish have a cartilaginous skeleton, that is, it is made up of cartilage. Its skin is covered with placoid scales, which are curved towards the posterior end of the fish. Also, they lack a swim bladder, which is the buoyancy organ. Some of the animals that derive from this class are the shark, the ray, sharks and chimeras.
osteichthyes
These fish are the opposite of the cartilaginous class, since, as their name indicates, they maintain a bony skeleton, like a swim bladder. However, the characteristics of the fish of this class have been changing, since in some cases there is a transformation of the bladder into a type of lung. Also, they enjoy rayed fins and other lobed ones.
Types of fish according to the water
Fish vary their habitat depending on the type of water they are in, as these aquatic animals tend to suffer from certain vulnerabilities if they are not in the right waters. Because their physical conditions only allow them to develop in that type of water, as well as provide them with the nutrients they need.
Freshwater or tropical fish
They are fish that spend most of their life in freshwater such as rivers or lakes, since it is their natural habitat. In the same way, they can originate from these waters or adapt, since they have a lower salinity compared to other fish. They are characterized by being the most popular due to how cheap their care is, most people interested in having fish as a pet opt for these striking species.
Betta fish
They are known as fighters because of their strong aggressiveness towards others of the same species. These come in different colors that are very striking and bright, they also have very attractive fins that give them a harmonious shape.
spike fish
It is a very peaceful vertebrate and is easy to reproduce. Its body is elongated and usually measures about 10 cm maximum. Another name with which they identify it is Rainbow of Madagascar due to the bright colors they have, it has large eyes and a mouth in an upward direction.
neon fish
It is one of the most popular to have as pets, as they have a great capacity for resistance, as long as the quality of the water allows it. This has to be filtered, abundant and acidic. They require good care because otherwise, we can lose them before their time.
Catfish
As its name indicates, it resembles the feline, since tentacles sprout from its face that give the impression of whiskers. They are very quiet and large, so they need ample space. It is usually called a fish tank vacuum because they spend their time swimming at the bottom of it.
saltwater fish
These fish are the ones that live in the ocean, normally we can get them in an aquarium. According to fish characteristics of the sea, these have a high salinity level due to their physiology, which allows them to live in waters where the concentration of salt is higher. Also, they can live as well as swim alone or together.
Damsel fish
They have an aggressive temperament among themselves, in addition to being very shy, so they need a large space. They are adaptable and resistant to changes in the environment, they usually measure 7 cm and prefer to be alone. They are recommended for those just starting out with saltwater pets.
Clownfish
They are well known and adaptable to changes in the environment, however, conditioning their habitat is somewhat delicate. They have very bright colors and usually live in coral reefs protected by anemones. They maintain a good friendship, since they protect them from the bacteria that constantly enter their mouths, thus characterizing them as peaceful, although in some cases they can be aggressive with others.
goby fish
They are able to adapt to changes in temperature, but very slight. They have a small size, reaching 10 cm. They come in different shapes and colors, they also feed on the parasites of other species. Just as they defend those who provide shelter and sustenance, such as crustaceans.
Magenta Dwarf Perch
They do not require such a large space, but they do require shelters to hide. They have a territorial temperament with the species smaller than them. They have very vivid and bright colors, they are also hermaphrodites.
Cold water fish
They are easy fish to care for, they can live in waters with room temperature because they support lower temperatures than other tropical fish. They are considered very famous in the aquarium hobby, and their ideal temperature is 20 ºC, although it can vary between 18 and 24 ºC.
Goldfish
With a high level of popularity, these were the first to be domesticated and present variety among themselves. These omnivorous fish are characterized by being resistant but not insurmountable. Because they grow up to 30 cm, they need ample space, as well as not mixing them with others.
Pink Barbossa
They have a pink color almost similar to orange, they are not solitary because they prefer to live with their species. Although they can survive in this state, but they adopt a shy demeanor. They are omnivorous and usually measure 14 cm in their natural habitat.
paradise fish
They are very exotic due to their striking colors, which range from blue, orange, yellow, red and more. They have beautiful fins that make them coveted by fish fans, they measure approximately between 7 and 10 cm. Their temperament is territorial and aggressive, more so in males that tend to bite the fins of others.
galaxy fish
They stand out for their intense colors, in addition to being very small since they measure up to 1,5 cm. Their temperament varies according to the breeding season or stress levels, they need to live in a group, although the males can become a bit aggressive.
How is the feeding of the fish?
To know what do fish eat? It might not be a difficult question to answer, since we usually think that these animals feed on water and algae. But, the feeding of the fish depends on their habitat, and they usually feed on other smaller aquatic animals. The vast majority of fish are carnivorous, however, there are species that consume plants and algae. They are divided into four large groups, these are:
- The carnivores they are the largest, which feed on other smaller species. They have a short digestive system and their stomach is large.
- The herbivores They are those whose diet is based on vegetables and algae, they have a long intestine and a less voluminous stomach.
- The limenivores They feed on vegetables and debris, they have a great ability to dig at the bottom of the water and search for food.
- The omnivores These aquatic vertebrates consume all kinds of food, both vegetables and others of the same species. That is, they are both carnivores and herbivores.
How can fish swim?
Most of the fish have several fins to swim in the sea, some are used to propel themselves through the water, and others to guide their body while swimming. Being able to move in very dense waters thanks to the fact that they have a body with a hydrodynamic shape.
In addition, their body is covered by a layer of viscous liquid called mucosa, which allows water to slide through them without slowing them down. As they have powerful muscles in their trunk and tail that help propel their body forward, in some cases using their fins as a rudder.
The fish, with the exception of a few, swim in a serpentine way, accelerating the body and tail by pressing against the water, like a snake on the ground.
Why don't fish sink?
As mentioned, among fish characteristics they are found to possess a swim bladder. Said organ that fish have, has an oval shape and can vary in other species. It is based on a bag of flexible walls filled with gas that is located under the spine, this organ is responsible for controlling the floating of the fish in the water without the need for any muscular effort. Well, being full of air, the body of the fish is light and floats, on the contrary it happens when it is filled with water, depending on the amount they can submerge.
