Introduction to the Living Animal

Transcription

1 Introduction to the Living Animal Danilo Villar Rogayan Jr. Faculty, Department of Natural Sciences College of Teacher Education, Arts and Sciences RMTU San Marcelino 1.1. Zoology: The Study of Animals Zoology (Gr. zoon, logos, to study) is the study of animals. It is one of the broadest fields in all of science because of the immense variety of animals and the complexity of the processes occurring within animals. There are, for example, over 20,000 described species of bony fishes and over 300,000 described species of beetles! 1.1. Zoology: The Study of Animals It is no wonder that zoologists usually specialize in one or more of the subdisciplines of zoology. They may study particular functional, structural, or ecological aspects of one or more animal groups or they may choose to specialize in a particular group of animals. The study of zoology can be viewed as a series of efforts to analyze and classify animals. Attempts at classification as early as 400 BC are known from documents in the Hippocratic Collection. Aristotle, however, was the first to devise a system of classifying animals that recognized a basic unity of plan among diverse organisms. 1

2 Aristotle arranged groups of animals according to mode of reproduction and habitat. His Historia Animalium contains accurate descriptions of extant animals of Greece and Asia Minor. He was also interested in form and structure and concluded that different animals can have similar embryological origins and that different structures can have similar functions. In Roman times Pliny the Elder compiled four volumes on zoology in his 37-volume treatise called Historia Naturalis. Greek physician Galen, dissected farm animals, monkeys, and other mammals and described many features accurately, although some were wrongly applied to the human body. In the 17th century, the English physician William Harvey established the true mechanism of blood circulation. Until the Middle Ages, zoology was a conglomeration of folklore, superstition, misconception, and descriptions of animals, but during the 12th century it began to emerge as a science. St. Albertus Magnus denied many of the superstitions associated with biology and reintroduced the work of Aristotle. The anatomical studies of Leonardo da Vinci were far in advance of the age. His dissections and comparisons of the structure of humans and other animals led him to important conclusions. 2

3 Belgian physician Andreas Vesalius is considered the father of anatomy; he circulated his writings and established the principles of comparative anatomy. Classification dominated zoology throughout most of the 17th and 18th centuries. The Swedish botanist Carolus Linnaeus developed a system of nomenclature that is still used today. The study of comparative anatomy was extended by such men as George Cuvier, who devised a systematic organization of animals based on specimens sent to him from all over the world. Matthias Schleiden and Theodor Schwann, proved that the cell is the common structural unit of living things. The cell concept provided impetus for progress in embryology, founded by the Estonian scientist Karl Ernst von Baer, and for the development by a Frenchman, Claude Bernard, of the study of animal physiology, including the concept of homeostasis. 3

4 The most famous expedition was the voyage of the Beagle in the early 1830s. During this voyage, Charles Darwin observed the plant and animal life of South America and Australia and developed his theory of evolution by natural selection. The Austrian monk Gregor Mendel first formulated the concept of particulate hereditary factors later called genes Specializations in Zoology 1.3. Specializations in Zoology Anatomy: Study of the structure of entire organisms and their parts. Cell Biology: Study of the structure and function of cells. Ecology: Study of the interaction of organisms with their environment. Embryology: Study of the development of an animal from the fertilized egg to birth or hatching. Genetics: Study of the mechanisms of transmission of genes from parents to offspring. Histology: Study of tissues. Molecular biology: Study of subcellular details of animal structure and function. Parasitology: Study of animals that live in or on other organisms at the expense of the host Specializations in Zoology Physiology: Study of the function of organisms and their parts. Systematics: Study of the classification of, and the evolutionary interrelationships among, animal groups. Zoogeography: study of the distribution of animals over the earth 4

5 1.3. Specializations in Zoology By Taxonomic Group Entomology: Study of insects Herpetology: Study of amphibians and reptiles Ichthyology: Study of fishes Malacology: Mollusks Mammalogy: Study of mammals Ornithology: Study of birds Protozoology: Study of protozoa Animals share a common evolutionary past and evolutionary forces that influenced their history. Evolutionary processes are remarkable for their relative simplicity, yet they 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 existed in the past and have become extinct. Zoologists must understand evolutionary processes if they are to understand what an animal is and how it originated. Organic evolution (L. evolutus, unroll) is change in populations of organisms over time. It is the source of animal diversity, and it explains family relationships within animal groups. Charles Darwin published convincing evidence of evolution in 1859 and proposed a mechanism that could explain evolutionary change. 5

6 Since that time, biologists have become convinced that evolution occurs. The mechanism proposed by Darwin has been confirmed and now serves as the nucleus of our broader understanding of evolutionary change. Evolution not only explains why animals appear and function as they do, but it also explains family relationships within the animal kingdom. Like all organisms, animals are named and classified into a hierarchy of relatedness. Although Karl von Linne ( ) is primarily remembered for collecting and classifying plants, his system of naming binomial nomenclature has also been adopted for animals. A two-part name describes each kind of organism Zoology: An Ecological Perspective Ecology (Gr. okios, house; logos, to study) is the study of the relationships between organisms and their environment. Throughout our history, humans have depended on animals, and that dependence too often has led to exploitation. We depend on animals for food, medicines, and clothing. 6

7 1.5. Zoology: An Ecological Perspective Two problems, global overpopulation and the exploitation of world resources, are the focus of our ecological concerns. 1. Population. Global overpopulation is at the root of virtually all other environ-mental problems. It is estimated that the world population will reach 10.4 billion by the year As the human population grows, the dis-parity between the wealthiest and poorest nations is likely to increase Zoology: An Ecological Perspective Two problems, global overpopulation and the exploitation of world resources, are the focus of our ecological concerns. 2. World Resources Human overpopulation is stressing world resources. Continued use of fossil fuels adds more carbon dioxide to the atmosphere, contributing to the greenhouse effect and global warming. Deforestation of large areas of the world results from continued demand for forest products and fuel Zoology: An Ecological Perspective Solutions An understanding of basic ecological principles can help prevent ecological disasters. Understanding how matter is cycled and recycled in nature, how populations grow, and how organisms in our lakes and forests use energy is fundamental to preserving the environment. Unless we deal with the problem of human overpopulation, however, solving the other problems will be impossible. Summary 1. Zoology is the study of animals. It is a broad field that requires zoologists to specialize in one or more subdisciplines. 2. Animals share a common evolutionary past and evolutionary forces that influenced their history. 3. Evolution explains how the diversity of animals arose. 4. Evolutionary relationships are the basis for the classification of animals into a hierarchical system. This classification system uses a two-part name for every kind of animal. Higher levels of classification denote more distant evolutionary relationships. 7

8 Summary References 5. All animals share a common environment, and ecological principles help us to understand how animals interact within that environment. 6. Human overpopulation is at the root of virtually all other environ-mental problems. It stresses world resources and results in pollution, global warming, deforestation, and the extinction of many plant and animal species. Catchillar, Gerry C Biology: A Simplified Approach. Mandaluyong City: Echanis Press Inc. Hickman, Cleveland P., et al Integrated Principles of Zoology. Quezon City: Copyright by Times Mirror/ Mosby College Publishing and Printed by JMC Press, Inc. Krohne, David T General Ecology, 2nd Edition. Cengage Learning Asia Pte Ltd: Singapore. Microsoft Encarta Miller, Kenneth R. and Levine, Joseph S Prentice Hall Biology. Boston, Massachusetts: Pearson Education, Inc., publishing as Pearson Prentice Hall. Miller, Stephen A. and John P. Harley Zoology, Fifth Edition. The McGraw-Hall Companies. Nowicki, Stephen Biology. Canada: McDougal Littell, a division of Houghton Mifflin Company. Postlethwait, John H. and Janet L. Hopson The World of Biology. Pasay City, Philippines: Cengage Learning Asia Pte Ltd. Storer, Tracy I., et al General Zoology, Sixth Edition. Cubao, Quezon City: Philippine Copyright by McGraw Hill Inc and Printed by Atlas Publishing Co,, Inc. Wikipedia.com Youtube.com Lakô hãsalamát! Zambal for Maraming salamat! 8