Vertebrate animals are those that have an internal skeleton, which can be bony or cartilaginous, and belong to thesubphylum of chordates , that is, they have a dorsal chord or notochord and are made up of a wide group of animals, in which we find everything from fish to mammals. These share some characteristics with the other subphyla that make up the chordates, but have developed new and novel features that allow them to be separated within the taxonomic classification system.
This group has also been called skulls, which refers to the presence of a skull in these animals, whether of composition bone or cartilage. However, the term has been referred to by some scientists as outdated. Biodiversity identification and classification systems estimate that there are more than 60,000 species of vertebrates, a clearly diverse group that occupies practically all the planet's ecosystems. In this article on our site, we present the classification of vertebrate animals
How are vertebrate animals classified?
Currently, there are two types of classification of vertebrate animals: the traditional Linnaean and the cladistic Although traditionally the Linnaean classification, recent studies conclude that the cladistic classification establishes some different criteria regarding the classification of these animals.
In addition to explaining these two ways of classifying vertebrate animals, we will also present a classification based on the most general characteristics of invertebrate groups.
Vertebrate animals according to the traditional Linnaean classification
The Linnaean classification is a system accepted worldwide by the scientific community that provides a practical and useful way to categorize the world of living beings. However, with advances, especially in areas such as evolution and therefore in genetics, some classifications framed in this line have had to be modified over time. Under this classification, vertebrates are divided into:
Superclass Agnatos (no jaws)
In this category, we find:
- Cephalaspidomorphs: This is an extinct class.
- Hyperoartios: here come the lampreys (such as the species Petromyzon marinus) and the aquatic animals, with elongated and gelatinous bodies.
- Mixines: commonly known as hagfish, which are marine animals with quite elongated and very primitive bodies.
Superclass Gnathostomes (with jaws)
Here they are grouped:
- Placoderms: a class now extinct.
- Acanthodians: another extinct class.
- Chondrichthyans: where cartilaginous fish such as the blue shark (Prionace glauca) and the ray fish, such as the Aetobatus, are grouped narinari, among others.
- Osteichthyes: They are commonly known as bony fishes, among which we can mention the species Plectorhinchus vittatus.
Superclass Tetrapoda (with four limbs)
Members of this superclass also have jaws. Here we find a varied group of vertebrate animals, which is made up of four classes:
- Amphibians.
- Reptiles.
- Birds.
- Mammals.
These animals have managed to develop in all possible habitats, being spread all over the planet.
Vertebrate animals according to cladistic classification
With the advancement of evolutionary studies and the optimization of research in genetics, cladistic classification emerged, which classifies the diversity of living beings based precisely on the evolutionary relationshipsIn this type of classification there are also differences and it will depend on various factors, so there are no absolute precisions for the respective grouping. According to this area of biology, vertebrates are generally classified as:
- Cyclostomes: Fish without jaws, such as hagfish and lampreys.
- Chondrichthyans: Cartilaginous fish, such as sharks.
- Actinopterygian: bony fish, such as trout, salmon, and eels, among many others.
- Dipnoos: Lungfish, such as salamander fish.
- Amphibians: toads, frogs and salamanders.
- Mammals: whales, bats and wolves, among many others.
- Lepidosaurs: lizards and snakes, among others.
- Testudines: the turtles.
- Arcosaurs: crocodiles and birds.
Here you can see more examples of vertebrate and invertebrate animals.
Other classifications of vertebrate animals
Vertebrates have been grouped together because they share as a common feature the presence of a defined skull that provides protection to the brain andbony or cartilaginous vertebrae that surround the spinal cord. But, on the other hand, depending on certain particular characteristics, they can also be classified more generally in:
- Agnatos: includes hagfish and lampreys.
- Gnathostomes: where fish, jawed vertebrates with fin-forming limbs, and tetrapods, which are all other vertebrates, are found.
Another form of general classification is:
- Amniotes: refers to the development of the embryo in a fluid-filled sac, as is the case in reptiles, birds and mammals.
- Anamniotas: highlights cases in which the embryo does not develop in a fluid-filled sac, where we can include fish and amphibians.
As we have been able to show, there are certain differences between the classification systems of vertebrate animals, and this then suggests the level of complexity that has this process of identifying and grouping the biodiversity of the planet. In this sense, it is not possible to establish absolute criteria in the classification systems, however, we can have a notion of how vertebrate animals are classified, a fundamental aspect to understand their dynamics and evolution within the planet.
