Taxonomy

Taxonomy is the scientific discipline responsible for classifying, ordering and naming living beings in different categories, with the aim of establishing evolutionary relationships and understanding biological diversity. Taxonomy is based on the observation of morphological, physiological, molecular and ecological characteristics of organisms, and uses a hierarchical system of categories to group living beings into different levels, from the most general to the most specific.

The most commonly used classification system in taxonomy is Linnaeus’ system, which divides living things into kingdoms, phyla, classes, orders, families, genera, and species. According to this system, living beings are grouped into five kingdoms: Monera (bacteria), Protista (unicellular organisms), Fungi (fungi), Plantae (plants) and Animalia (animals).

Taxonomy is fundamental to scientific research in biology, as it allows the identification of new organisms and the understanding of the evolutionary relationships between them. It is also important for biodiversity conservation and natural resource management, as it provides information on the distribution and ecology of living things.

Linnaeus system

The Linnaean system is a system of taxonomic classification of living beings created by the Swedish naturalist Carl von Linné in the eighteenth century. This system uses a hierarchy of categories, from the most general to the most specific, to classify and name agencies.

Linnaeus’ system consists of seven hierarchical categories that are used to classify living things. These categories are as follows:

Kingdom

It is the highest category in the taxonomic hierarchy and is used to classify living things into large groups according to their general characteristics. In Linnaeus’ system, living things are classified into five kingdoms: Monera, Protista, Fungi, Plantae,  and Animalia.

Edge

It is a category that is used to group living beings according to their structural characteristics. The phyla are very diverse and are made up of different groups of organisms.

Class

It is a category that is used to group living beings that have similar structural and functional characteristics.

Order

It is a category that is used to group living beings that have more specific structural and functional characteristics.

Family

It is a category that is used to group living things that have even more specific structural and functional characteristics.

Gender

It is a category that is used to group living beings that have very similar structural and functional characteristics.

Species

It is the lowest category in the taxonomic hierarchy and is used to uniquely identify living things. A species is defined as a group of organisms that have similar morphological, physiological and reproductive characteristics and that can exchange genes with each other.

Linnaeus’ system has been very useful in the classification of living things and has served as the basis for modern taxonomy. However, this system has limitations and does not always reflect the complexity of evolutionary relationships between organisms. For this reason, other more complex taxonomic classification systems based on molecular genetics have been developed.

Kingdom category

In biology, the kingdom is the highest taxonomic category in the classification hierarchy of living things. Organisms are grouped into different kingdoms based on their general characteristics, such as their cellular structure, their mode of nutrition and their way of reproduction.

Historically, different classification systems have been proposed and different numbers of kingdoms have been recognized. The most widely used system today recognizes five major kingdoms:

Monera: This kingdom includes prokaryotic single-celled organisms, such as bacteria and cyanobacteria (also known as blue-green algae).

Protista: This kingdom includes single-celled organisms and some eukaryotic multicellular organisms that are not plants, animals, or fungi. Examples include single-celled algae, protozoa, and mucilaginous molds.

Fungi: This kingdom includes absorption-feeding eukaryotic organisms, such as fungi, mushrooms, and lichens.

Plantae: This kingdom includes eukaryotic organisms that are capable of photosynthesis, such as land plants, algae and some photosynthetic bacteria.

Animalia: This kingdom includes eukaryotic organisms that are heterotrophic and feed on other organisms, such as animals, insects, and fish.

It should be noted that, in some classification systems, other kingdoms are included or different names are used for the mentioned kingdoms. In addition, the classification of living things remains an active field of research and new species and evolutionary relationships are continuously being discovered, so the classification system is subject to changes and revisions in the future.

Phylum category

The phylum is a taxonomic category used to group organisms according to their structural and anatomical characteristics. This category is the third in the hierarchy of classification of living beings, after the kingdom and the subkingdom.

Organisms belonging to the same phylum share similar structural and developmental characteristics, suggesting that they are closely related evolutionarily. For example, organisms belonging to the phylum Chordata have a similar body structure, with a notochord, a dorsal nerve structure, and a postanal tail  at some point in their development.

There are numerous phyla in the animal kingdom, some of which are as follows:

• Porifera: includes organisms known as sponges, which are sessile and filtering animals.
• Cnidarians: includes organisms such as jellyfish, corals, and anemones, which have stinging cells called cnidocytes.
• Flatworms: includes flatworms, which can be free-living or parasitic.
• Annelids: includes segmented worms, such as earthworms and leeches.
• Mollusks: includes shelled animals, such as snails and clams, as well as squid and octopus.
• Arthropods: includes animals with articulated legs and exoskeletons, such as insects, arachnids and crustaceans.
• Echinoderms: includes animals such as starfish, sea urchins and sea cucumbers, which have a calcareous skeleton.
• Chordates: includes animals with notochord, such as fish, amphibians, reptiles, birds, and mammals.

Each phylum can also be divided into subphyla, classes, orders, families, genera and species, each of which represents a more specific level in the classification hierarchy of living beings.

It is important to note that the classification of organisms into phyla is not always accurate and is subject to constant change and revision as new species are discovered and evolutionary relationships between groups deepen. In addition, some organisms may be difficult to classify in a specific phylum due to their unique characteristics or lack of sufficient information about their anatomy and physiology.

Class category

• The taxonomic class category is used to group organisms according to their shared morphological, anatomical, and physiological characteristics. This category is below the edge and above the order in the hierarchy of classification of living beings.
• The classes group organisms that share more specific characteristics than phyla, suggesting that they are more closely related evolutionarily. For example, organisms belonging to the class Mammalia share characteristics such as milk production to feed their young and hair or skin to regulate body temperature.

Some important classes in the animal kingdom are as follows:

• Birds: Includes animals with wings and feathers, such as birds, poultry and penguins.
• Mammals: includes animals with mammary glands that produce milk to feed their young, such as humans, dogs, cats, and elephants.
• Reptiles: Includes scaly skin animals, such as snakes, lizards, and turtles.
• Amphibians: includes animals that go through an aquatic larval stage and an adult terrestrial stage, such as frogs, toads and salamanders.
• Fish: Includes aquatic animals with gills and scales, such as freshwater fish and saltwater fish.
• Insects: includes animals with three pairs of legs and an exoskeleton, such as beetles, bees, and butterflies.

Each class in turn can be divided into orders, families, genera and species, providing an increasingly specific classification hierarchy. However, it is important to note that classifying organisms into classes and other levels of the classification hierarchy is a constantly evolving and changing task, as new species are discovered and evolutionary relationships between groups deepen.

Order Category

• The taxonomic category of order is one of the main categories in the classification hierarchy of living things. It is above the family and below class in the classification of organisms. Organisms belonging to the same class are often divided into several orders, representing different groups based on specific characteristics.
• For example, in the class Mammalia, there are several distinct orders, such as primates, carnivores, rodents, ungulates, and cetaceans. Each of these orders has distinctive features that differentiate it from the others, such as the presence of claws in carnivores, elongated incisor teeth in rodents, or hooves in ungulates.
• The order category can be useful for scientists studying evolution and the relationships between different groups of organisms. By grouping organisms into different orders, scientists can identify patterns in the evolution of specific traits and determine how species have adapted and diversified over time.

Some examples of animal orders include:

• Order Carnivora: includes animals such as lions, tigers, bears, wolves, foxes and raccoons.
• Order Primates: includes animals such as monkeys, apes and humans.
• Order Rodentia: includes animals such as mice, rats, squirrels, beavers and porcupines.
• Order Cetacea: includes animals such as whales, dolphins and porpoises.
• Order Artiodactyla: includes animals such as cows, pigs, deer and giraffes.

Each order in turn can be divided into families, genera, and species, providing an increasingly specific classification hierarchy. It is important to note that classifying organisms into orders and other levels of the classification hierarchy is a constantly evolving and changing task, as new species are discovered and evolutionary relationships between groups deepen.

Family Category

The taxonomic category of family is one of the categories in the hierarchy of classification of living beings. It is above gender and below order. Families group organisms that share morphological, anatomical, and physiological characteristics more specific than orders, suggesting that they are more closely related evolutionarily.

Families are often named after a representative genus, and often include several species within that genus. For example, the Felidae family  includes cats, lions, tigers, jaguars and other felines, and is named after the genus Felis.

Some examples of families in the animal kingdom include:

• Family Canidae: includes dogs, wolves, coyotes and foxes.
• Family Hominidae: includes humans and their closest evolutionary relatives, such as chimpanzees and gorillas.
• Family Felidae: includes cats, lions, tigers, jaguars and other felines.
• Family Elephantidae: includes African and Asian elephants.
• Family Ursidae: includes bears, such as the brown bear, the polar bear and the black bear.

Each family in turn can be divided into subfamilies, genera and species, providing an increasingly specific classification hierarchy. The classification of organisms into families and other levels of the classification hierarchy is a constantly evolving and changing task, as new species are discovered and evolutionary relationships between groups deepen.

Gender category

The taxonomic category of genus is one of the main categories in the classification hierarchy of living things. It is above the species and below the family. Genera group organisms that share similar characteristics, but are not necessarily distinctive enough to be classified in a higher category, such as family.

Genre names are always capitalized and may be based on morphological, anatomical, physiological or molecular characteristics. For example, the genus Canis includes dogs, coyotes and wolves, and is characterized by sharp teeth and elongated snouts.

Some examples of genera in the animal kingdom include:

• Genus Homo: includes humans and our closest evolutionary relatives, such as Homo neanderthalensis.
• Genus Panthera: includes big cats, such as lion, tiger, leopard and jaguar.
• Genus Canis: includes dogs, coyotes and wolves.
• Genus Felis: includes domestic cats and other small felines.
• Genus Equus: includes horses, zebras and donkeys.

Each genus in turn can be divided into species, providing an increasingly specific classification hierarchy. It is important to note that classifying organisms into genera and other levels of the classification hierarchy is a constantly evolving and changing task, as new species are discovered and evolutionary relationships between groups deepen.

Species category

The taxonomic category of species is the most basic unit of classification of living things. It is below the genus and above the subspecies and is used to describe organisms that share similar characteristics and that can reproduce with each other and have fertile offspring.

Each species has a binomial scientific name, composed of two parts: the genus and the species. The scientific name is written in italics or underlined and the first word, the genus, is capitalized, while the second, the species, is written in lowercase. For example, the scientific name of humans is Homo sapiens, where Homo is the genus and sapiens is the species.

The scientific name of a species is universally accepted and allows precise and unambiguous communication about organisms. Scientific names are based on morphological, anatomical, physiological and molecular characteristics, and often reflect evolutionary history and relationships between groups of organisms.

Some examples of species in the animal kingdom include:

Homo sapiens: the human species.

Canis lupus: the gray wolf.

Panthera leo: the lion.

Felis catus: the domestic cat.

Equus ferus: the horse.

It is important to note that classifying organisms into species and other levels of the classification hierarchy is a constantly evolving and changing task, as new species are discovered and evolutionary relationships between groups deepen.

Observation of morphological characteristics

The observation of morphological features is a technique commonly used in biology to classify and study organisms. Morphological features are those that can be seen with the naked eye or with the help of a magnifying glass or microscope, and may include the shape, size, color, texture, and structure of an organism or its parts.

The observation of morphological characteristics is an important part of the process of identifying and classifying organisms. For example, to identify a plant species, you can look at its leaves, stems, flowers, fruits, and seeds to determine its shape, size, texture, color, and other characteristics. Similarly, to identify a species of insect, you can observe its shape, size, number of legs, antennae, wings and other anatomical details.

It is important to note that, although the observation of morphological characteristics is a valuable technique for the classification of organisms, it is not always sufficient to determine the true evolutionary relationship between them. Morphological features may be similar between species that are not closely related evolutionarily, while closely related species may have subtle morphological differences.

Therefore, the observation of morphological features is often combined with other techniques, such as molecular analysis, to provide a more accurate and complete classification of organisms.

Observation of physiological characteristics

The observation of physiological characteristics refers to the study of the biological functions of an organism, such as respiration, circulation, metabolism, digestion, excretion, reproduction and the nervous system. These physiological characteristics can provide valuable information about the inner workings of an organism and its adaptation to its environment.

Observation of physiological characteristics is important in biology because many of these biological functions are shared by different organisms, which can help classify them into taxonomic groups. For example, the presence of a closed circulatory system, which carries blood around the body, is a common physiological feature in vertebrates and can be used to classify them into a separate subclass of invertebrates.

Physiological characteristics can also be used to study the adaptations of organisms to their environment. For example, organisms that live in extreme environments, such as deserts or deep oceans, may have unique physiological adaptations to survive in those conditions. These adaptations may include the ability to store water, tolerate high temperatures or pressures, or use alternative energy sources.

Observation of physiological characteristics can also be useful for studying diseases and disorders. For example, observing the function of the immune system in response to an infection can help understand how the body works to fight disease.

In summary, the observation of physiological characteristics is important in biology because it can provide valuable information about the inner workings of organisms, their adaptation to their environment, and the body’s response to disease and disorders.

Observation of molecular characteristics

The observation of molecular characteristics refers to the study of the molecules that make up organisms, such as DNA, RNA, and proteins. These molecules can provide valuable information about the evolutionary relationship between organisms, their biological function, and their adaptation to their environment.

Observing molecular characteristics is important in biology because molecules are the basis of life and many of them are shared by different organisms, which can help classify them into taxonomic groups. For example, DNA analysis can help determine the evolutionary relationship between different species and how they relate to other taxonomic groups.

Molecular features can also be used to study the biological function of organisms. For example, analyzing proteins can help identify their biological function and how they interact with other molecules in the body.

In addition, observation of molecular characteristics can also be useful for studying diseases and disorders. For example, DNA analysis can help identify mutations that can cause genetic diseases and protein analysis can help identify abnormal proteins that are associated with neurodegenerative diseases.

In summary, the observation of molecular characteristics is important in biology because it can provide valuable information about the evolutionary relationship between organisms, their biological function and their adaptation to their environment, as well as for studying diseases and disorders.

Observation of ecological character

The observation of ecological characteristics refers to the study of the interaction between organisms and their environment, including biotic and abiotic factors. These characteristics can provide valuable information about the distribution, adaptation, and diversity of organisms in different ecosystems.

The observation of ecological characteristics is important in biology because organisms do not exist in isolation, but are in constant interaction with other organisms and their environment. Ecological characteristics can be used to understand how organisms adapt to their environment, how they interact with other organisms, and how they influence the ecosystems they inhabit.

Ecological characteristics include abiotic factors such as temperature, humidity, water availability, light, topography and geology of the environment. They also include biotic factors such as predation, competition, and symbiosis relationships between organisms.

Observation of ecological characteristics can be useful for studying biodiversity and ecosystem conservation. For example, observing the distribution and abundance of different species in an ecosystem can provide valuable information about their conservation status and factors that may be affecting their survival.

In addition, observing ecological characteristics can also be useful for understanding the effects of climate change and other environmental changes on ecosystems and the organisms that inhabit them.

In summary, the observation of ecological characteristics is important in biology because it can provide valuable information about the adaptation, interaction and diversity of organisms in different ecosystems, as well as to study biodiversity, conservation and the effects of environmental change.