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Zoos are institutions for exhibiting and studying wild animals. Many contemporary zoos have also made environmental education and the conservation of biodiversity part of their mission. "Zoo" is a term derived from the Greek zoion, meaning "living being." As a prefix it indicates the topic of animals, such as in zoology (knowledge of animals) or zoogeography (the distribution and evolutionary ecology of animals). As a noun it is a popular shorthand for all zoological gardens and parks.

Design and operation

Zoological gardens and parks are complex institutions involving important factors of design, staffing, economics, and politics. Design of a zoo is a compromise between the needs of the animals (e.g., light, temperature, humidity, cover, feeding areas, opportunities for natural behavior), the requirements of the staff (e.g., offices, libraries, research and veterinary laboratories, garages, storage sheds), and amenities for visitors (e.g., information, exhibitions, restaurants, rest areas, theaters, transportation ).

Zoos range in size from as little as 2 acres (0.8 ha) to as much as 3,000 acres (1,231 ha), and animal enclosures may range from small cages to fenced-in fields. The proper size for each enclosure is determined by many factors, including the kind and number of species being exhibited and the extent of the enclosure's natural or naturalistic landscaping. In small zoos, space is at a premium. Cages and paddocks are often arranged into taxonomic or zoogeographic pavilions, with visitors walking among the exhibits. As a collection of animals in a confined and artfully arranged space, these zoos are called zoological gardens. In larger zoos, more space is generally available. Enclosures may be bigger, the landscaping more elaborate, and cages fewer in number. Nonpredatory species such as hoofed mammals may roam freely within the confines of the zoo's outer perimeter. Visitors may walk along raised platforms or ride monorail trains through the zoo. Lacking the confinement and precise arrangement of a garden, these zoos are called zoological parks. Some zoos take go a step farther and model themselves after Africa's national parks and game preserves . Visitors drive cars or ride buses through these "safari parks," observing animals from vehicles or blinds.

A zoo's many functions are reflected in its staff, which is responsible for the animals' well-being, exhibitions, environmental education, and conservation programs. There are several job categories: administrators, office personnel, and maintenance staff tend to the management of the institution. Curators are trained wildlife biologists responsible for animal acquisition and transfer, as well as maintaining high standards of animal care. Keepers perform the routine care of the animals and the upkeep of their enclosures. Veterinarians focus on preventive and curative medicine, guard against contagious disease, heal stress-induced ailments or accidental injuries, and preside over births and autopsies. Well-trained volunteers serve as guides and guards, answering questions and monitoring visitor conduct. Educators and scientists may also be present for the purpose of environmental education and research.

Zoos are expensive undertakings, and their economy enables or constrains their resources and practices. Few good zoos produce surplus revenue; their business is service, not profit. Most perpetually seek new sources of capital from both public and private sectors, including government subsidies, admission charges, food and merchandise sales, concessionaire rental fees, donations, bequests, and grants. The funds are used for a variety of purposes, such as daily operations, animal acquisitions, renovations, expansion, public education, and scientific research. The precise mixture of public and private funds is situational. As a general rule, public money provides the large investments needed to start, renovate, or expand a zoo. Private funds are better suited for small projects and exhibit startup costs.

A variety of public and private interests claim a stake in a zoo's mission and management. Those concerned with the politics of zoos include units of government, regulatory agencies, commercial enterprises, zoological societies, non-profit foundations, activist groups, and scholars. They influence the availability and use of zoo resources by holding the purse strings and affecting public opinion. Conflict between the groups can be intense, and ongoing disputes over the use of zoos as entertainment, the acquisition of "charismatic megafauna" (big cute animals), and the humane treatment of wildlife are endemic.

History and purposes

Zoos are complex cultural phenomena. Menageries, the unsystematic collections of animals that were the progenitors of zoos, have a long history. Particularly impressive menageries were created by ancient societies. The Chinese emperor Wen Wang (circa 1000 b.c.) maintained a 1,500 acre (607 ha) "Garden of Intelligence." The Greek philosopher Aristotle (384-322 b.c.) studied animal taxonomy from a menagerie stocked largely through the conquests of Alexander the Great (356-323 b.c.). Over 1,200 years later, the menagerie of the Aztec ruler Montezuma (circa a.d. 1515) rivaled any European collection of the sixteenth century.

In the main, these menageries had religious, recreational, and political purposes. Ptolemy II of Egypt (300-251 b.c.) sponsored great processions of exotic animals for religious festivals and celebrations. The Romans maintained menageries of bears, crocodiles , elephants , and lions for entertainment. Powerful lords maintained and exchanged wild and exotic animals for diplomatic purposes, as did Charlemagne (a.d. 768-814), the medieval king of the Franks. Dignitaries gawked at tamed cheetahs strolling the botanical gardens of royal palaces in Renaissance Europe. Indeed, political and social prestige accrued to the individual or community capable of acquiring and supporting an elaborate and expensive menagerie.

In Europe, zoos replaced menageries as scholars turned to the scientific study of animals. This shift occurred in the eighteenth century, the result of European voyages of discovery and conquest, the founding of natural history museums, and the donation of private menageries for public display. Geographically representative species were collected and used to study natural history, taxonomy, and physiology. Some of these zoos were directed by the outstanding minds of the day. The French naturalist Georges Leopold Cuvier (1769-1832) was the zoological director of the Jardin de Plants de Paris (founded in 1793), and the German geographer Alexander von Humboldt (1769-1859) was the first director of the Berlin Zoological Garden (founded in 1844). The first zoological garden for expressly scientific purposes was founded by the Zoological Society of London in 1826; its establishment marks the advent of modern zoos.

Despite their scientific rhetoric, zoological gardens and parks retained their recreational and political purposes. Late nineteenth century visitors still baited bears, fed elephants, and marveled at the exhausting diversity of life. In the United States, zoos were regarded as a cultural necessity, for they reacquainted harried urbanites with their wilderness frontier heritage and proved the natural and cultural superiority of North America. As if recreation , politics, and science were not enough, an additional element was introduced in North American zoos: conservation. North Americans had succeeded in decimating much of the continent's wildlife, driving the passenger pigeon (Ectopistes migratorius ) to extinction , the American bison (Bison bison ) to endangerment, and formerly common wildlife into rarity. It was believed that zoos would counteract this wasteful slaughter of animals by promoting their wise use. At present, zoos claim similar purposes to explain and justify their existence, namely recreation, education, and conservation.

Evaluating zoos

Critics of zoos contend they are antiquated, counterproductive, and unethical; that field ecology and wildlife management make them unnecessary to the study and conservation of wildlife; and that zoos distort the public's image of nature and animal behavior, imperil rare and endangered wildlife for frivolous displays, and divert attention from saving natural habitat . Finally, critics hold that zoos violate humans' moral obligations to animals by incarcerating them for a trivial interest in recreation. Advocates counter these claims by insisting that most zoos are modern, necessary, and humane, offering a form of recreation that is benign to animal and human alike and is often the only viable place from which to conduct sustained behavioral, genetic, and veterinary research.

Zoos are an important part of environmental education. Indeed, some advocates have proposed "bioparks" that would integrate aquariums, botanical gardens, natural history museums, and zoos. Finally, advocates claim that animals in zoos are treated humanely. By providing for their nutritional, medical, and security needs, zoo animals live long and dignified lives, free from hunger, disease, fear, and predation.

The arguments of both critics and advocates have merit, and in retrospect, zoos have made substantial progress since the turn of the century. In the early 1900s, many zoos collected animals like postage stamps, placing them in cramped and barren cages with little thought to their comfort. Today, zoos increasingly use large naturalistic enclosures and house social animals in groups. They often specialize in zoogeographic regions, permitting the creation of habitats which plausibly simulate the climate , topography , flora , and fauna of a particular environment . Additionally, many zoos contribute to the protection of biodiversity by operating captive-breeding programs, propagating endangered species , and restoring destroyed species to suitable habitat.

This progress notwithstanding, zoos have limitations. Statements that zoos are "arks" of biodiversity, or that zoos teach people how to manage the "megazoo" called nature, greatly overstate their uses and lessons. Zoos simply cannot save, manage, and reconstruct nature once its genetic, species, and habitat diversity is destroyed. That said, the promotion by zoos of environmental education and biodiversity conservation is an important role in the defense of the natural world.

[William S. Lynn ]



Croke, V. The Modern Ark: The Story of Zoos: Past, Present, and Future. Collingdale: DIANE Publishing Co., 2000.

McKenna, V., W. Travers, and J. Wray, eds. Beyond the Bars: The Zoo Dilemma. Northamptonshire, UK: Thorsons Publishing Group, 1988.

Page, J. Zoo: The Modern Ark. New York: Facts On File, 1990.


Foose, T. J. "Erstwild & Megazoo." Orion Nature Quarterly 8 (Spring 1989): 6063.

Robinson, M. H. "Beyond the Zoo: The Biopark." Defenders 62 (November-December 1987): 1017.

Stott, J. R. "The Historical Origins of the Zoological Park in American Thought." Environmental Review 5 (Fall 1981): 5265.

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