Introduction to Zoology

Zoology: The Study of Animals

• Zoology is the comprehensive study of animals
• Zoology is one of science’s broadest fields due to the diversity and complexity of animals
• Over 20,000 species of bony fish have been described
• Over 300,000 species of animals total have been described
• Zoologists specialize in zoology subdisciplines
• Zoology specialization involves studying functional, structural, or ecological aspects of animal groups
• Zoology specialization can also involve studying a particular group of animals

History of Zoology

• The study of zoology is viewed as analyzing and classifying animals
• Classifications were attempted as early as 400 BC, found in the "Hippocratic Collection"
• Aristotle devised a system of classifying animals that recognized a basic unity among diverse organisms
• Aristotle arranged animals by mode of reproduction and habitat
• Aristotle’s "Historia Animalium" contains accurate descriptions of extant animals of Greece and Asia Minor
• Aristotle concluded that different form/structure in animals shows similar embryological structure and functions
• Pliny the Elder compiled four volumes on zoology in his 37-volume treatise called "Historia Naturalis" during Roman times
• Galen, a Greek physician, dissected farm animals, monkeys, and other mammals
• Galen accurately described many features, although some features were wrongly applied to the human body
• William Harvey, an English Physician from the 17th century, established the true mechanism of blood circulation
• Until the Middle Ages, zoology was a conglomeration of folklore, superstition, misconception, and description of animals
• In the 12th century zoology started to emerge as a science
• St. Albertus Magnus denied biology superstitions, and reintroduced the work of Aristotle
• Leonardo da Vinci's anatomical studies were far in advance of the age
• Da Vinci compared human and animal structures, leading to important conclusions
• Andreas Vesalius, a Belgian physician, is considered the "father of anatomy"
• Vesalius circulated his writings and established the principles of comparative anatomy
• Classification dominated zoology throughout most of the 17th and 18th centuries
• Carolus Linnaeus, a Swedish botanist, developed a system of nomenclature that is still in use today
• Georges Cuvier extended comparative anatomy by devising an animal organization system based on worldwide specimens
• Matthias Schleiden (plants) and Theodor Schwann (animals) proved that the cell is the common structural unit of living things
• Karl Ernst Von Baer founded embryology
• Claude Bernard developed the study of animal physiology, including the concept of homeostasis
• Charles Darwin observed the plant and animal life of South America and Australia during the voyage of the Beagle in the early 1830s
• Darwin developed his theory of evolution by natural selection
• Gregor Mendel, an Australian monk, first formulated the concept of particulate hereditary factors, later called genes

Specializations in Zoology

• Anatomy involves studying the structure of entire organisms and their parts
• Cell Biology involves studying the structure and function of cells
• Ecology involves studying the interaction of organisms with their environment
• Embryology involves studying the development of an animal from the fertilized egg to birth or hatching
• Genetics is the study of how genes are transmitted from parents to offspring
• Histology involves the study of tissues
• Molecular Biology involves studying subcellular details of animal structure and function
• Parasitology involves the study of animals that live in/on other organisms at the host’s expense
• Physiology involves studying the function of organisms and their parts
• Systematics involves studying the classification/evolutionary interrelationships among animal groups
• Zoogeography involves studying the distribution of animals over the earth
• Entomology: is the study of insects
• Herpetology: is the study of amphibians and reptiles
• Ichthyology: is the study of fishes
• Malacology: is the study of mollusks
• Mammalogy: is the study of mammals
• Ornithology: is the study of birds
• Protozoology: is the study of protozoa

Zoology: An Evolutionary Perspective

• Animals share a common evolutionary past and evolutionary forces that have influenced their history
• Evolutionary processes are remarkable for their simplicity but have had awesome effects on life-forms
• These processes have resulted in an estimated 4 to 30 million species of organisms living today
• Only 1.4 million species have been described
• Many more species existed in the past and have become extinct
• Zoologists must understand evolutionary processes to understand what an animal is and how it originated
• Organic evolution is change in populations of organisms over time
• Organic evolution is the source of animal diversity, and it explains relationships within animal groups
• Charles Darwin published evidence of evolution in 1859 and proposed a mechanism that could explain evolutionary change
• Biologists are convinced that evolution occurs
• Darwin's proposed mechanism serves as the nucleus of our broader understanding of evolutionary change
• Evolution explains why animals appear and function, and it explains family relationships within the animal kingdom
• Animals are named and classified into a hierarchy of relatedness
• Karl von Linne is primarily remembered for collecting/classifying plants
• Linne’s naming - binomial nomenclature-has been adopted for animals
• A two-part name describes each kind of organism
• Ecology is the study of the relationships between organisms and their environment
• Throughout our history, humans have depended on animals, which has too often led to exploitation
• We depend on animals for food, medicines, and clothing

Zoology: An Ecological Perspective

• Global overpopulation and world resource exploitation are the focus of our ecological concerns
• Global overpopulation is at the root of virtually all other environmental problems
• The world population will reach 10.4 billion by the year 2100, it is estimated
• As the human population grows, the disparity between the wealthiest and poorest nations is likely to increase
• Human overpopulation is stressing world resources
• The continued use of fossil fuels adds more carbon dioxide to the atmosphere
• Carbon dioxide contributes to the greenhouse effect and global warming
• Deforestation of large areas of the world results from continued demand for forest products and fuel
• Gaining an understanding of basic ecological principles can help prevent ecological disasters
• Understanding matter being cycled and recycled in nature, along with population growth, and how organisms use energy in the lakes/forests is fundamental to preserving the environment
• Unless we deal with the problem of human overpopulation, solving the other problems will be impossible