What is Zoology, Definitions, its History, Branches and Careers

What do You Know About Zoology?

Zoology is the branch of biology that deals with laboratory animals and the animal kingdom. Also known as animal biology. The zoology study includes the relationship between the animal kingdom and the environment such as taxonomy, habits, structure, embryology, distribution, evolution, and extinct species.

The Greek philosopher Aristotle was the first to classify living things in the 4th century BCE. He divided living things into animals and plants and continued to classify them. Then terms like biology, botany, and zoology were born.


What is Zoology


Zoological studies involve animals’ performance, behavior, and interactions with other species in the environment. It is a miracle that describes the distribution of every species on earth, including the extinct ones. In addition to the animal kingdom and the environment, zoology also explores new areas of research.

Aristotle then divided animals into two groups: one with red blood and one without worms and four marine animals. Then he collected creatures that could walk, walk and swim.

Aristotle was classified by the 16th century, during the Enlightenment; The scientist then took another look. Today, zoology has become more complex, with living beings divided into five kingdoms, with animal species divided into different groups, such as clans, classes, orders, families, genera, and finally species

These phenomena are part of Charles Darwin’s theory of evolution and natural selection. In 1859, Charles Robert Darwin added the theory of evolution to the scientific evidence.

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Historical Background

Ancient man’s life as a hunter revealed his relationship with other animals, food sources, and damage. As human traditions evolved, animals were incorporated into human traditions and philosophies as human companions. Livestock farming has led to a more systematic and considered approach to animal welfare, especially since urbanization and increased animal production.

In his study of the animal world, which the ancient Greeks attributed to modern, if not scientific, forms of the disease — previously thought of as demons — Hippocrates became powerful when bodily organs malfunctioned. An early text in which the systematic study of animals was encouraged by extensive descriptions of living things, and his work compares it to the Greek concept of the order of nature and the complex forms of nature.

During the Roman period, Pliny compiled a 37-volume Historical Naturalist, a collection of anecdotes and facts about celestial bodies, geology, animals, plants, metals, and stones. Books VII and XI deal with zoology; the eighteenth chapter on land animals begins with the largest animal, the elephant. Pliny’s views were naive, but his scientific work, as formal work, had profound and lasting effects.

Areas of study

Although knowledge of many areas of animal biology such as anatomy and morphology is still useful, Biochemistry and molecular biology; cell biology; developmental studies (embryology); environmental sciences; on the boundaries of the fields of zoology

Anatomy of Morphology

The description of the shape and internal structure is one of the earliest records of animal biology. Aristotle was an animal collector and anatomist. He identified different levels of structural complexity associated with life, behavior, and organs. Aristotle had no system of classification, but he clearly saw animals as going from the simplest to the most complex.

Humans are more complex than animals and because they are more intelligent, they occupy a higher position in a special category. The ideas of the leaders of the ecological world of the time came in handy in the last century

After Aristotle’s study of the Mediterranean, centered in Alexandria, the study of anatomy, especially the digestive system, developed rapidly and was the first to be known for its study. Galen studied anatomy in Alexandria in the second century AD. and divided many animals.

Over time, the contributions of Renaissance medical experts Andreas Vesalius, such as Galen, although they have a medical background, have enhanced the growth of the sense of touch. Many similarities have been found in the behavior of different animals and many books have been published documenting these things.

Taxonomy or Systematics

It is in the works of Carolus Linnaeus that the diversity of life is treated authoritatively. Linnaeus sought to find a “natural way,” now known as an intuitive understanding of the relationship of the sexes, that represented evolutionary descent from a common ancestor; However, Linnaeus’ way of organizing nature is very similar to the concept of ideal morphology in that he wants to define the size of the “type” as the size of the species.

In terms of classification of nomenclature, Linnaeus made revolutionary progress by introducing a Latin binomial system: each species was assigned a Latin name, independent of the local name, and appeals were made to Latin authorities. time. The Latin name is divided into two parts.

The first word in the Latin name for the common chimpanzee, for example, pan troglodytes, refers to the broad category or species to which chimpanzees belong; The second term is the name of the species within the species. In addition to genera and species, Linnaeus also recognized other taxonomic groups, or taxa (single taxa), which are still in use today; namely order, class and kingdom, poly family (between species and order) and phyla (between class and kingdom).

Each can be subdivided into lower or higher prefixes, such as subfamilies or superclasses. Linnaeus’s main work, the Systema Naturae, went through 12 editions during his lifetime; The 13th and final edition was published posthumously. Although biodiversity approaches have been extensively elaborated, modified by taxonomic categories, and improved by ongoing work – for example, Linnaeus considered whales to be fish – they still define ways and means, even in the use of Latin names, for now. labor nomenclature.


The practical implications of physiology have always been a necessary concern of people in both medicine and husbandry. Essentially, since Hippocrates, practical knowledge of the workings of the human body has been accumulated along with domesticated animals and plants. This knowledge expanded, especially from the early 1800s onwards, generally through experiments on animals known as comparative physiology. After Harvey demonstrated circulation, the experimental measure became widely used.

Since then, medical physiology has progressed rapidly; Famous texts appeared, such as the eight-volume Elementa Physiology Corporis Humani (Elements of Human Physiology) by Albrecht von Haller, which had a medical emphasis. At the end of the 18th century, the influence of chemistry on physiology was demonstrated by Antoine Lavoisier’s brilliant analysis of respiration as combustion.

This French chemist not only established that living organisms use oxygen but also opened the way for further research into the energy of living organisms. His research strengthened the mechanistic view, which argued that the same natural laws governed both the animate and inanimate spheres.

Embryology or Developmental Studies

Embryonic growth and differentiation have long been important biological problems. According to 17th-century developmental accounts, the adult human existed as a miniature (homunculus) that initiated the emergence of an embryo. However, in 1759, the German physician Caspar Friedrich Wolf firmly introduced the idea that undifferentiated substances are gradually and systematically classified into adult systems. Although these epigenetic processes are now accepted as common features of plant and animal development, many questions remain unresolved. French physician Marie-Francois Xavier Bishat stated in 1801 that differentiated parts are composed of different components called tissues. Further discoveries in cell theory led to the development of the cellular component of tissue.

The concept of epigenetic changes and the identification of structural factors have led to new interpretations of differentiation. It has been proven that the egg produces three primary germ cells, from which specialized organs containing cells are formed. Later, after the discovery of mammalian eggs, von Beer used this information in 1828 to examine the development of various members of the vertebrate group. It was then that embryology emerged as the distinct field we know today.


Darwin was not the first person to hypothesize that organisms can change and evolve from generation to generation, but he was the first to propose the mechanism of the accumulation of mutations. He proposed that genetic variation occurs in an endless race for survival and that mutations that promote survival are automatically maintained.

Thus, the accumulation of changes over time creates new forms. Survivors are better adapted to their environment because conservative mutations are associated with survival. Darwin called this process natural selection.

Many of Darwin’s predecessors, especially Jean-Baptiste Lamarck, wanted to accept the idea of ​​species diversity, but this meant ignoring Linné’s static doctrine of special creations and species. beings are the basis of change.

The contrast between the romanticism of Lamarck and the objective analysis of Darwin shows the kind of revolution that the concept of natural selection caused. Mechanistic explanations like those that form part of Harvey’s description of circulation were long available to biologists, but they did not understand the general structure of biological thought until the rise of Darwinism.


The issue of heredity was carefully considered before Mendel conducted his final analysis. Like Darwin’s predecessor, Mendel wanted to determine and explain all genetic traits transmitted by blood or by various “fluid fluids” and other independent components in organisms. Studying plants allowed Mendel to distance himself from a single, anthropomorphic explanation.

By examining seven dichotomies, such as long or short, red or white flowers, spanning three generations, we can establish a traditional pattern that can be applied to all types of breeding. Darwin, in search of an explanation for heredity, never saw Mendel’s work published in 1866 in his obscure journal of the Natural History Society. It was discovered simultaneously by three European geneticists in 1900.

Cellular and Molecular Biology

Although cells were recognized as the basic building blocks of life in the early 1800s, perhaps the most exciting period of research occurred in the 1940s. The 19th and early 20th centuries saw further empirical studies that were processed from light microscopy to dynamic molecular investigations involving vital life.

In effect, cell theory is a generalization based on microscopic observations of many species of plants and animals.

Rudolf Virchow, German cytopathology, coined a basic term about cells in the phrase Omnis cellula e cellula (from cell to all cells). Cell reproduction is the basis for continued life; Stem cells are not only the most important structural component of life but also the foundation of the body and genetics. The new insights provided by the principles of the cellular organization have implications for all areas of biology.

The study of cells is very important in animal biology, especially when combined with embryology. Heredity influences the continuation of cell formation through reproduction. Not surprisingly, Wilson’s centennial study of stem cell biology was titled The Cell: Its Role in Development and Heredity.


First introduced by Haeckel in the late 19th century as “ecology” (from the Greek “house, Oikos”), the term ecology refers to the habitat of living things in nature. In the 90s, several scientists from Europe and America participated. He laid the foundation for modern research into natural ecosystems and the populations of organisms that inhabit them.

Animal ecology, the science that studies the relationship between consumers and their environment, is highly complex. His research efforts are usually focused on specific aspects. For example, some studies use special adaptations to address human environmental problems (e.g. water conservation in desert animals). Others may refer to the species’ role in that ecosystem or the ecosystem itself.

For different ecosystems, the order of the food chain is determined and their energy and mass transfer efficiencies are calculated to give an idea of ​​their capacity. That is, productivity can be precisely determined by the number of organisms or the weight of organisms at a particular level of the food chain (see biosphere).

Despite advances in our understanding of animal ecology, the zoological discipline still lacks the fundamental unified theoretical principles of genetics (genetic theory) or evolution (natural selection).

Methods in Zoology

Animal research can focus on different topics, such as ecosystems and their environments, organisms, cells, and chemical reactions, so each Research Type requires its own approach. As attention is focused on the molecular basis of genetics, development, physiology, behavior, and ecology, technologies related to the cell and its many components are increasingly important.

Therefore, microscopy is an important skill in animal science, as are other physicochemical techniques for separating and identifying molecules. Information technology plays an important role in analyzing the lives of animals. These new methods are used in addition to many traditional methods such as measurements and experiments at the tissue, organ, organ system, and biological level.


With the continued development of techniques that make the components of cells clearly visible, the light used in microscopy can now be manipulated to reveal certain unknown structures in living cells. The latter must be present in the environment to destroy cells.

But the undeniable advantage of the electron microscope is its high magnification power. In theory, it can separate individual atoms; In biology, however, lower magnifications are more useful for determining the structures of whole cells and the nature of the molecules that make up them.

Separation and Purification Techniques in Zoology

Characterization of the components of cellular systems is important for biological research. For example, the specific molecular structure of a cell influences its size and mass (mass per unit volume); As a result, cellular components stabilize (and can) stabilize at different rates during centrifugation in a centrifuge.

Other cleaning methods depend on different conditions. Molecules differ in the positive or negative polarity of the electric field. The movement towards or away from these columns occurs at different speeds for different molecules, causing them to separate. This method is called electrophoresis.

To separate the sugar water molecules, use the fact that the molecules have different solubility so that they go into different states when the enzyme moves. This process, called chromatography because of the dye used to identify substances, produces samples of exceptional quality.

Applied Zoology

The role of Zoology in Livestock farms to produce feed (meat, milk), hides, wool, organic fertilizer, and various chemicals. Livestock productivity has increased dramatically since the 1870s, mainly due to selective breeding and improved animal feed. The purpose of breeding is to breed strong breeding stock, so it is possible to breed.

The heritable component is separated from environmental factors by determining the heritability coefficient, which is defined as the ratio of the variance of the gene-controlled trait to the total variance.

Another aspect of food production is pest control. The adverse effects of some chemical pesticides make it important to take effective and safe control measures. Livestock – commercial fishing. Fish farming and fisheries management (such as rice farming in Asia) are important parts of this industry.

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