For other uses, see Zoology (disambiguation).
"Animal biology" redirects here.
For the academic journal, see Animal Biology (journal).
"Zoologist" redirects here.
For the academic journal, see The Zoologist.
Zoology (/zoʊˈɒlədʒi/) is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems.
Ancient history to Darwin
Main article: History of zoology (through 1859)
Although the concept of zoology as a single coherent field arose much later, the zoological sciences emerged from natural history reaching back to the biological works of Aristotle and Galen in the ancient Greco-Roman world.
Prominent in this movement were Vesalius and William Harvey, who used experimentation and careful observation in physiology, and naturalists such as Carl Linnaeus, Jean-Baptiste Lamarck, and Buffon who began to classify the diversity of life and the fossil record, as well as the development and behavior of organisms.
Over the 18th, 19th, and 20th centuries, zoology became an increasingly professional scientific discipline.
Explorer-naturalists such as Alexander von Humboldt investigated the interaction between organisms and their environment, and the ways this relationship depends on geography, laying the foundations for biogeography, ecology and ethology.
Cell theory provided a new perspective on the fundamental basis of life.
Main article: History of zoology (since 1859)
In 1859, Darwin placed the theory of organic evolution on a new footing, by his discovery of a process by which organic evolution can occur, and provided observational evidence that it had done so.
The result was a reconstruction of the classification of animals upon a genealogical basis, fresh investigation of the development of animals, and early attempts to determine their genetic relationships.
In the early 20th century, the rediscovery of Mendel's work led to the rapid development of genetics, and by the 1930s the combination of population genetics and natural selection in the modern synthesis created evolutionary biology.
Understanding the structure and function of cells is fundamental to all of the biological sciences.
The similarities and differences between cell types are particularly relevant to molecular biology.
It focuses on how organs and organ systems work together in the bodies of humans and animals, in addition to how they work independently.
Anatomy and cell biology are two studies that are closely related, and can be categorized under "structural" studies.
Physiology studies the mechanical, physical, and biochemical processes of living organisms by attempting to understand how all of the structures function as a whole.
The theme of "structure to function" is central to biology.
Physiological studies have traditionally been divided into plant physiology and animal physiology, but some principles of physiology are universal, no matter what particular organism is being studied.
For example, what is learned about the physiology of yeast cells can also apply to human cells.
The field of animal physiology extends the tools and methods of human physiology to non-human species.
For example, it generally involves scientists who have special training in particular organisms such as mammalogy, ornithology, herpetology, or entomology, but use those organisms as systems to answer general questions about evolution.
Evolutionary biology is partly based on paleontology, which uses the fossil record to answer questions about the mode and tempo of evolution, and partly on the developments in areas such as population genetics and evolutionary theory.
Following the development of DNA fingerprinting techniques in the late 20th century, the application of these techniques in zoology has increased the understanding of animal populations.
Biological classification is a form of scientific taxonomy.
Modern biological classification has its root in the work of Carl Linnaeus, who grouped species according to shared physical characteristics.
Biological classification belongs to the science of zoological systematics.
Many scientists now consider the five-kingdom system outdated.
Modern alternative classification systems generally start with the three-domain system: Archaea (originally Archaebacteria); Bacteria (originally Eubacteria); Eukaryota (including protists, fungi, plants, and animals) These domains reflect whether the cells have nuclei or not, as well as differences in the chemical composition of the cell exteriors.
Further, each kingdom is broken down recursively until each species is separately classified.
The scientific name of an organism is generated from its genus and species.
For example, humans are listed as Homo sapiens.
Homo is the genus, and sapiens the specific epithet, both of them combined make up the species name.
When writing the scientific name of an organism, it is proper to capitalize the first letter in the genus and put all of the specific epithet in lowercase.
Additionally, the entire term may be italicized or underlined.
The dominant classification system is called the Linnaean taxonomy.
It includes ranks and binomial nomenclature.
A merging draft, BioCode, was published in 1997 in an attempt to standardize nomenclature, but has yet to be formally adopted.
Branches of zoology
Although the study of animal life is ancient, its scientific incarnation is relatively modern.
Since Hunter and Cuvier, comparative anatomical study has been associated with morphography, shaping the modern areas of zoological investigation: anatomy, physiology, histology, embryology, teratology and ethology.
Modern zoology first arose in German and British universities.
In Britain, Thomas Henry Huxley was a prominent figure.
His ideas were centered on the morphology of animals.
Many consider him the greatest comparative anatomist of the latter half of the 19th century.
Similar to Hunter, his courses were composed of lectures and laboratory practical classes in contrast to the previous format of lectures only.
Gradually zoology expanded beyond Huxley's comparative anatomy to include the following sub-disciplines:
- Zoography, also known as descriptive zoology, is the applied science of describing animals and their habitats
- Comparative anatomy studies the structure of animals
- Animal physiology
- Behavioral ecology
- Ethology studies animal behavior
- Invertebrate zoology
- Vertebrate zoology
- Soil zoology
- The various taxonomically oriented disciplines such as mammalogy, biological anthropology, herpetology, ornithology, ichthyology, and entomology identify and classify species and study the structures and mechanisms specific to those groups.
- Evolutionary biology: Development of both animals and plants is considered in the articles on evolution, population genetics, heredity, variation, Mendelism, and reproduction.
- Molecular biology studies the common genetic and developmental mechanisms of animals and plants
- Palaeontology: Study of fossils of the life forms that are now extinct.
- Systematics, cladistics, phylogenetics, phylogeography, biogeography, and taxonomy classify and group species via common descent and regional associations.
- Animal science, the biology of domesticated animals
- List of zoologists
- Outline of zoology
- Timeline of zoology
- Zoological distribution
Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Zoology.