Zoology is a science that is concerned with animal life. It deals with the study of animal structure, internal processes and modes of life, their evolution and their interaction with one another and with their environment. It also consists of understanding the manner by which animals grow and reproduce, the principles of inheritance, and the distribution of animal life over the Earth today and in past geologic time.
For a student, a simple classroom lecture series on zoology maybe enough, with some samples of actual specimens, looking through a microscope for minute animals or frog dissection... but learning should be more than that. Students may also have educational trips in zoos, petshops, museums, botanical gardens, parks, or a trip to the countryside in order to learn more, specially animal relationships with its natural habitat and how animals actually live
Zoology as a Science
The word science comes from the Latin word scientia which means knowledge. Scientists use a number of methods in obtaining knowledge. These methods include: (1) Observing Nature;(2) Classifying Data; (3) Using Logic; (4) Conducting experiment; (5) Forming a Hypothesis; and (6) Expressing findings mathematically.
Scientific study can be divided into four major groups: (1) mathematics and logic; (2) the physical sciences; (3) the life sciences; and (4) the social sciences. The life sciences, also called the biological sciences or biology, if concerned with the study of living organisms. There are 6 Kingdoms of Living Organisms, namely: (1) Archaebacteria; (2) Eubacteria; (3) Fungi; (4) Plantae; (5) Animalia; and (6) Protista. Zoology is concerned with the study of the fifth group of living organisms – the animals.
SUBDIVISIONS OF ZOOLOGY
(1) Systematic Zoology -- (a) Taxonomy – study of classification of animals;(b) Ecology – study of the relationship of animals with their environment; (c) Zoogeography – study of the distribution of animals on earth; (d) Animal Evolution – study how the existing kinds of animals came into being.
(2) Morphology; -- studies the structural aspect of the animal body, its branches includes: (a) Anatomy – study of animal structure as revealed by gross dissection; (b) Comparative Anatomy – study of the various animal types from the lowest to the highest form, with the aim of establishing homologies; its origin, and modification of body structures; (c) Histology – study of tissues as revealed by the microscope; (d) Cytology – study of the minute parts and functions of animal cells; (e) Embryology – study of the formation and early development of the organism; and (f) Paleontology – study of past life as revealed by fossils.
(3) Experimental Zoology – concerned with experimental alterations of the patterns of organisms. Its branches includes: (a) Genetics – study of heredity à Phenotype = Genotype + Environment + (G x E); (b) Experimental Morphology – study of animal structures; (c) Embryology – study of growth and development from fertilization to birth / hatching.
(4) Molecular Biology -- (a) Biochemistry – study of chemical make-up of living tissues;
(b) Genetics – study of the chemistry of genes; (c) Chemistry of Macromolecules – chemistry of make up of large molecules that make up living matter.
Zoology may also be subdivided into groups according to animal subject like:
(1) Entomology – insects; (2) Helminthology – worms with special reference to parasitic forms; (3) Herpetology – reptiles and amphibians; (4) Ornithology – birds; (5) Parasitology – parasitic organisms; (6) Ichthyology – fishes; (7) Mammalogy – mammals.
THE ORIGIN OF LIFE
There are various theories and hypotheses that explain the origin of living things. Most of them are based on scientific explanations except the religious ones which are based solely on faith.
1. Religious Explanation – creation stories of most religions explain the origin of life. These stories tell how the world and living things were created by a Divine Being - God. One Example is the book of Genesis. … however, each religion has their own concept of a creationist view… nevertheless, they also provides us some clues in the origin of life and the universe.
2. The Theory of Spontaneous Generation (Abiogenesis theory). – the theory that originated from ancient times claiming that lower forms of life have arisen from non-living matter. An example is the view that flies developed from decaying meat; that mice formed from piles of old rags; mudfish and frogs rises from dried field mud drenched with rain… However, Italian scientist Francesco Redi In the 1600’s conducted experiments which showed that meat protected from flies would not produce maggots. However, Redi’s experiments did not end the dispute over spontaneous generation. A belief persisted that microscopic forms of life could arise spontaneously and the argument raged for about 200 years. French chemist Louis Pasteur settled the controversy in the mid 1800’s. He demonstrated that even the minutest bacteria do not arise spontaneously but always grow from other bacteria. Most biologists accepted the idea that all life comes from existing life.
3. Biogenesis Theory – a theory that states that “all life comes only from pre-existing life”.
4. Theory of Panspermia – theory that states that spores from some other part of the universe (or from Mars) landed on Earth and began to develop. However, some scientists doubt that spores could survive a journey through the harsh conditions of outer space. It explains only the origin of life on the earth and not how life arose in the universe.
5. Theory of Chemical Evolution – theory developed by Alexander I. Oparin and J.B.S. Haldane that claims that life developed though a series of spontaneous chemical reactions in the atmosphere and oceans of early Earth – absence of oxygen – in the process forming the first organic molecules (proteins or amino acids) which becomes RNA then into DNA… and also through the theory, the first cell developed. This is now accepted by most biologists.
CHARACTERISTICS OF LIVING THINGS – These what distinguishes living things from non-living things…
1. They share a chemical uniqueness
2. Basic Unit is the Cell
3. They Reproduce
4. All are based on a universal genetic code (DNA) / program
5. They grow & develop
6. They excrete waste by-products
7. They obtain & use Materials to produce energy (eat and metabolize).
8. They respond to their environment – (irritability / excitability)
9. They maintain a stable internal environment (Homeostasis) and able to repair their body.
10. As a group, living things evolve, That is, they change over time as they are “naturally selected. This is based on fossil records
11. Possess complexity and hierarchical organization (orderliness)
12. Undergo metabolism (food eaten is utilized and becomes part of their bodies)
13. Environmental interaction
14. Obeys physical laws of physics and chemistry -- entropy and conservation of energy.
