When we talk about Vertebrate animals, we refer to all those who have a backbone that divides their body into two equal parts, skull and tail, they have the ability to adapt to any type of environment, even the most difficult. Find out all about these species!
What are Vertebrate Animals?
The Vertebrate animals They are a very diverse set of species of the animal Kingdom, what differentiates them from other animal species is that they have a backbone that is made up of vertebrae, currently some 72.327 species belong to the group of vertebrates, including fossils of animals that are extinct.
These animals are capable of adapting to any environment, including the most inhuman and difficult to inhabit. It is believed that these species appeared in the Cambrian period, about 530 million years ago, their origin originally from freshwater aquaculture, a huge variety of forms that developed in the ocean and many years later on land.
The term "vertebrata" is similar to "Craniata", which also includes the so-called hagfish or compass fish, which do not have true vertebrae and the lampreys or primitive fish that lack jaws and have outlines of vertebrae called arcualia, together with the gnathostomes that almost always have vertebrae.
The skeleton of vertebrates fossilizes easily, which has been of great help in understanding their evolutionary process.
If we refer to their taxonomy, these animals belong to the group of the subphylum vertebrata, one of the groups of the phylum chordates or chardata, a division of the animal kingdom in which there are forms that have a dorsal neural tube, gills, dorsal chord and tail at some stage of its embryonic process.
According to research on the genetics of hagfish and lampreys, they belong to a species called Cyclostomata within Vertebrata. According to new fossil findings, they maintain that hagfish also belong to vertebrates, that is to say that hagfish have descendants of vertebrates that do not have a jaw and that in the process of evolution lost their vertebrae.
Features
In summary, it could be said that the characteristics of the Vertebrate animals
- They have bilateral symmetry, that is, they are divided into two halves and have a skull which protects the brain, their bones are cartilaginous or bony and they have a backbone or backbone. For scientists there are currently approximately 62.000 species of this type.
- The body of vertebrate animals is divided into three zones: head, trunk and extremities, in addition to some having a tail; the trunk of mammalian animals is both subdivided into abdomen and thorax. In terrestrial vertebrates, the respiratory system is pulmonary.
- If we talk about aquatic species, we can say that they have fins in the middle position, vertebrates that have jaws protrude the paired extremities of the trunk. They show notochord in the embryo stage, which when they are adults replaces the vertebral column and most of their sensory organs and nerves are attached to their head.
- They have a branchial respiratory system, which means that while the embryo grows, the walls of the body form slits or holes in the pharynx that give way to the gills of fish and different species. Their skeletal structure can be cartilaginous, bone and sometimes dermoskeleton, that is, they have bone formations of epidermal origin.
Structure of the Organism in Vertebrate Animals
The physical characteristics of all these animals are very varied, as they belong to different types of animals, with different sizes, feeding, reproductive processes and other body systems that do not coincide in all species.
integument
The integument or membrane of vertebrates is of great importance in its structure due to the various functions it can fulfill and can show various differences in the corneas, this is usually the largest organic system of the animal that covers it completely.
In the integument you can see a layer that preserves the organism, epidermal formations such as fish scales or bony plates of turtle shells, and it has three covers in which we can find the dermis, epidermis and hypodermis. . On the other hand, the pigmentation of the membrane is due to the pigment cells and chromatophores of the skin.
Two types of formations originate in the skin of vertebrates:
- epidermal formations: These are glands called phaneras, that is, the complementary structure and visible above the skin, together with the skin, they constitute the integumentary system that can be composed of a large amount of proteins (which are sometimes poisonous, as in the case of many fish, reptiles and amphibians), sebaceous and sweat and mammary, for example; claws, nails, feathers and beaks. Hair, scales, hooves, among others.
- dermal formations: In these we can put as an example the shells of turtles, fish scales, crocodile scales, horns, among others.
Locomotor apparatus
In the Vertebrate animals, the musculoskeletal system has adjusted to its original function, which consists of swimming and performing varied movements of great complexity, according to its sensory needs.
The fish that existed in the primitive age and spread in the Seas and oceans, underwent many transformations of great importance, from the moment that the paired fins arose, which later changed again to become locomotor limbs or five-fingered chiridia.
Circulatory system
The circulatory apparatus of vertebrates is a closed circulatory system, in this system the circulating medium (blood) passes through blood vessels and serves as a means of transport for nutrients and oxygen to all body tissues. This system reaches various degrees of complexity according to the evolution of the animal, it is also responsible for removing waste that is a product of metabolism.
It has a blood system and a lymphatic system, with a heart distributed in chambers, arterioles, arteries, veins, venules, and capillaries. Fish have a systemic pathway and a bronchial pathway. Many land vertebrates have a double circulatory system, that is, the minor or pulmonary circulation and the major or general circulation, which means that venous and arterial blood do not mix.
respiratory system
The respiratory apparatus of vertebrates is branchial in water animals, as with cyclostomes, fish, and amphibian larvae. On the other hand, in terrestrial animals it is pulmonary, however, a group of water animals and also amphibians that have two types of respiration, pulmonary and dermal tissue.
Vertebrates have an organ called gills or threadlike appendage, they are internal or external depending on the animal's body and their function is respiratory, they are prepared for gas exchange in water. The gills have something in common and it is an extensive contact space with the environment, since in the gills the irrigation is more developed than in the rest of the body.
In birds, the respiratory system is very powerful, it supplies the precise oxygen to create the necessary force so that the organism is in excellent working order when flying. It has a system of bronchi that is linked to air sacs, its lungs are divided into lobules.
Nervous system
The nervous system of vertebrates consists of a central nervous system, within which we can differentiate two subsystems because it is very useful to us; the central and the peripheral. The central system is made up of the brain and spinal cord, while the peripheral system is made up of nerve fibers that transmit information between different parts of the body and the central system.
On the other hand, tetrapods have two thickenings in the spinal cord, the cervical and lumbar intumescences, this is a consequence of the growth of the legs.
The eyes are arranged in a lateral vision chamber (except in the case of some types of birds and primate mammals), which also include the tactile organs of mammals and the pressure-wave catcher lines of cyclostomes, fish and some amphibians of the water, the auditory organs in tetrapods consist of the inner ear and middle ear, oval and round windows, tympanic membrane, and ossicles.
Endocrine system
Likewise, we must emphasize that the endocrine system of Vertebrate animals It is regulated by the pituitary gland and the hypothalamus, this through the gestation of biochemical messages that perform their function on the pancreas, gonads, adrenal glands, among others, and this is well perfected by the hormones that perform multiple functions in the body.
Digestive apparatus
The digestive system of vertebrates are several organs linked together that form a long chain of processes in operation within the body, and all together are responsible for the process of assimilation and absorption of food, which are transformed so that nutrients can be consumed and spent by cells.
The vertebrates of prehistory fed by means of filtration systems, later they evolved and these were replaced, the pharynx was reduced and the gill slits, this with the exception of the jawless fish that are very primitive vertebrates, the other vertebrates were They were modified through the evolutionary process and became jaws, with which they capture their food. In short, the digestive system of these species is very complex.
The digestive system of vertebrate animals consists of the pharynx, the esophagus, the stomach, the oral cavity, the intestines and the anus, all these organs are intertwined with other attached glands, such as the salivary glands, the liver and the intestine. pancreas. Tetrapods have a growing oral cavity, that is, other auxiliary forms are displayed in it, such as the lips, palate, and tongue and teeth.
Excretory system
The excretory apparatus of vertebrates is made up of the sweat glands and the renal apparatus, it is a very complete system and on a par with the dependent chordates. By means of a special organization, it is possible to filter the internal liquids apart from the external environment, at the same time keeping the entire internal organism of these animals in balance.
Reproduction
Vertebrate animals reproduce sexually (except some marine ones, such as hermaphroditisms), that is, this commonly happens through the same species between two individuals of different genders, with external or internal fertilization in both viviparous and in oviparous.
In the case of mammals it is a little more complicated because in these, the embryo develops inside its mother, who feeds it through the placenta (in the case of placental mammals and marsupials), after the pups are born and feed on the milk secreted by their mammary glands.
evolutionary history
It is presumed that vertebrates arose in the middle of the Cambrian explosion (at the beginning of the Paleozoic period), together with another multiple group of fauna. The oldest known vertebrate is the Haikouichthys, with 525 million years of antiquity and is similar to the Current hagfish, although they did not have jaws, their skull and skeleton were cartilaginous.
The first reptiles arose in the Carboniferous period, the synapsids and anapsids that existed in abundant quantities in the Permian period, that is, in the final stretch of the Paleozoic, however, the diapsids were the vertebrates that predominated in the mesozoic era.
The dinosaurs gave rise to the birds in the Jurassic and together with their extinction at the end of the Cretaceous era, they also gave rise to the proliferation of mammals, which had existed for many years, approximately since the beginning of the synapsid reptiles, but in the Mesozoic were in the background.
The first fish with jaws or gnathostomes arose in the Ordovician and proliferated during the Devonian, which for this reason is called the age of fish and it was also in this period that many prehistoric agnathians became extinct, however the labyrinthodonts arose , species that switched between fish and amphibians.
Types of Vertebrate Animals
Vertebrate animals are divided into four large groups:
Chondrichthyes (chondrichthyes)
These are vertebrate fish with an internal skeleton, which is mostly cartilaginous, their teeth are not attached to the jaw and replace them as they eat away, for example: sharks, rays, mantas and chimaeras.
Osteichthyes (Osteichthyes)
This is the group where all fish whose internal skeleton is bony and have cartilaginous structures but only a small part belong. They are usually thermal mouth with attached dermal bones, from where the teeth come out and after their teeth fall out they don't come out again, for example; the giant grouper and the scorpion fish.
agnatha
These are all the vertebrate fish that do not have jaws and are similar to the eel, they are hematophagous because they do not process food in the same way as the rest of the fish, they feed on blood, necrophages, and corpses, for example ; lampreys and hagfish.
tetrapods
Also known as four-limbed animals, in this group we can find birds, mammals, reptiles and amphibians.
- Birds: Birds are vertebrate animals that are characterized by having feathers, they stand on their hind ends and the forelimbs develop into wings, however, although they have wings, not all of them can fly. Some examples of flying birds are the eagle, the parrot or macaw, the hawk, the hummingbird and the pelican.
- Mammals: Mammals are characterized by having hands, feet or legs, and hair, as well as having a jaw with dental bones and having mammary glands, for example; the dolphin, the lion, the horse, the dog and human beings, which are vertebrate mammals.
- Amphibians: These Vertebrate animals they are characterized by having an important muscular development in their limbs, which allows them to move by swimming or jumping, for example; the salamander, the toad, and the newt, which are invertebrates belonging to the group of amphibians.
- reptiles: These are of hard epidermis covered by keratin scales, they have very short or non-existent extremities, as in the case of snakes that move by crawling and are capable of laying eggs with shells, as an example we have the iguana, turtle and crocodile .
Classification according to your Body Temperature
At the same time, vertebrate animals can be divided according to their temperature and can be divided into two large groups that are:
- Vertebrates Endotherms: These are known as warm-blooded vertebrates, because their temperature is constant regardless of external causes, their temperature most of the time is between 34º C and 38º C.
- Vertebrates Ectotherms: These animals are also called cold-blooded vertebrates, since they can regulate their body temperature depending on the temperature of the environment, amphibians, fish and reptiles are from this group.
