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With so many mammal species in the World, there needed to be a system to differentiate them. In this article, we look at how mammals are classified.

Seven groups classify all living creatures, all with a two-part scientific name. This enables scientists to tell the difference between them from their names.

There are over 5,400 species of mammals in the World, with over four hundred of these found in North America. More species are being added to these numbers all the time, and identifying all the mammals can be a difficult job.  

Biologists use a system of classification to differentiate the many species of mammals. All different species have their unique species name. Groups are used to contain the species to which it has evolved. The groups are also known as taxa. This system is used for all animals, whether alive or extinct.

Want to know the difference between mammals and insects?  Find out in this article I wrote.

Seven Groups Of Classification

There are seven groups used in classifying animals.


Merriam-Webster Dictionary Definition

“A major category in biological taxonomy that ranks above the phylum and below the domain.”

All animals belong to the Kingdom of Animalia (animal). There are six kingdoms, which include animals (Animalia), plants (Plantae), fungi (Fungi), protists (Protista), Eubacteria (Eubacterium), and Archaebacteria (Archaebacterium).  

Animalia has the most species and is the most extensive Kingdom with over one million species.

Animalia is made up of six basic animal classes. These include invertebrates, fish, amphibians, reptiles, birds, and mammals.


Merriam-Webster Dictionary Definition

“A group that constitutes or has the unity of a phylum, specifically a primary category in biological taxonomy, especially of animals that ranks above the class and below the kingdom.”

A phylum contains one or more classes and their subgroups. A variety is a subdivision of the Kingdom. There are thirty-six groups, but mammals make up only one of these groups, Chordata.  

Chordata includes around 50,000 species.

Chordata includes all animals with a notochord, a dorsal hollow nerve, and a muscular postanal tail at some point in life. Some members of this species lose one or all of these features as they develop.


Merriam-Webster Dictionary Definition

“A group, set, or kind sharing common attributes: such as a major category in biological taxonomy ranking above the order and below the phylum or division.”

Class is a category or group that shares attributes or characteristics. There are one hundred and seven classes of animals, but only eight in the phylum Chordata. Mammals are all contained in one class, Mammalia. Mammals are from the Latin word Mammalia, which Linnaeus took from mammals, which means “of the breast,” and from mamma, “breast.”

Many mammals are classed as near threatened.  Find out more here


Merriam-Webster Dictionary Definition

“A class of persons or things grouped according to quality, value, or natural characteristics: such as a category of taxonomic classification ranking above the family and below the class.”

Order is the following classification, and there are currently 26 orders of mammals. Out of 26 orders, over 70% of all mammals come from three orders: Rodentia (rodents), Chiroptera (bats), and Soricomporpha (shrews and moles.)

If you want to know more about the different orders of mammals, I have written an article you can find here.


Merriam-Webster Dictionary Definition

“A group of related plants or animals forming a category ranking above a genus and below an order and usually comprising several to many genera.”

The 26 orders of mammals are further classified into 153 families of mammals.


Merriam-Webster Dictionary Definition

“A category of biological classification ranking between the family and the species, comprising structurally or phylogenetically related species or an isolated species exhibiting unusual differentiation, and being designated by a Latin or Latinized capitalized singular noun.”

The different families of mammals are divided further into genera. There are currently 1258 genera of mammals in the World. Genera include groups of species. These groups are structurally similar or phylogenetically related.

Many mammals hibernate during winter.  Please find out more in this article I wrote.


Merriam-Webster Dictionary Definition

“A category of biological classification ranking immediately below the genus or subgenus, comprising related organisms or populations capable of interbreeding, and being designated by a binomial that consists of the name of a genus followed by a Latin or Latinized uncapitalized noun or adjective agreeing grammatically with the genus name.”

There are over 5,400 species of mammals in the World. Together, the genus and the species make up the name that scientists identify animals. This name is called the binomial nomenclature.

How Does Classification Help Distinguish Between Animals?

Names of animals are identified as two scientific names. The first name is the genus that the mammal belongs to, and the second name is the name of their species.

Both of the scientific names are written in Latin, and this helps scientists all over the World. By using one language, scientists around the World can universally understand the terms. This two-part name also enables scientists to know precisely the animal type. With over one and a half million different species worldwide, scientists can recognize the type of animal from the scientific name.  

An example of this would be the gray wolf. If a scientist read the words gray wolf unless they know what it is, they would not know if this was a mammal, an insect, a fish, or an animal. The scientific (binomial) name of the gray wolf is Canis lupus. This advises the scientist that the genus is Canis, and the species name is lupus. Canis is a genus of Canidae, which contains canines. Lupus means wolf in Latin.

Where Do The Principles Of Classification Come From?


The name of taxonomy is the scientific classification of living organisms. Aristotle, who lived between 384-322 BC, was the first to classify organisms. Aristotle’s definitions lasted for two thousand years before being challenged.

Aristotle tried to classify all types of animals in History Animalium (History of Animals) by the kind of organism they were. Aristotle attempted to group all animals by their similarities to each other rather than genetics.

Aristotle believed that groups of animals could be ranked from lowest to highest, with humans at the top. 

Many animals fight, but not always for the same reason.  Please find out more in this article I wrote.

Aristotle also came up with a means of identification that is still used today. Binomial nomenclature is a two-part name that can identify any living creature or plant on Earth.  

We still use binomial names to classify living organisms, and Aristotle was the first to identify them by their genus and difference. We now use genus and species, but Aristotle explained each animal’s differences while keeping them grouped with similar animals (genus.) 

Although many botanists thought the years that had worked on different classification methods to name plants, there were very few that worked on animals.

With so many different methods of naming plants, many names could be used for the same plant. Taxonomy needed to be standardized, and in 1735, the principles of modern classification came from Carl Linnaeus’s work.

Carl Linnaeus

In the eighteenth century, Linnaeus, the Swedish explorer, and botanist, developed a way of naming all species so that people could tell them apart. In 1735, Linnaeus published Systema Naturae (The System of Nature.)  

The publication went through many revisions throughout his life, changing errors that he found. His work has carried on after his death, with others introducing genetic testing to his work.

The book organized all living creatures into different groups called kingdoms, classes, orders, genera, and species. Linnaeus also carried on the binomial naming that Aristotle had started, a system that we still use today.

Did you know there are five groups of marine mammals in North America?  If you want to know more, then click here.