INTRODUCTION :
–Taxomony (Gr.) - study of nomenclature, classification and their principles. This word was given by ''Candolle'' (Taxis – arrangements. Nomos - Law)
HISTORICAL BACKGROUND OF TAXONOMY :
–Aristotle : - ''father of zoology ''. (Book : Historia Animalium)
Father of ancient animal – Classification. He classified animals into two groups on the basis of their natural similarities and differences into –
(i) Anaima :- Those animals which don't have Red blood or in which RBC are absent e.g. Sponges, Cnidaria, Mollusca, Arthropoda. Echinodermata like Invertebrates.
(ii) Enaima :- These animals have red blood. This group includes all vertebrated and it has been further dvided into two sub groups.
(a) Vivipara :- It incldues animals which give birth to young-ones e.g. Man, Whale and other mammals.
(b) Ovipara :- It includes animals which lay eggs. e.g. Amphibians, Pisces, Aves, Reptiles etc.
–Pliny :- He classified animal into groups : -
(a) Flying
(b) Non-flying
–John-Ray :- He gave & defined the term '' species'' as the smallest unit of classfication. He gave ''concept of species ''. According to him, the organisms which develop from the similar type of parents, belong to the same-species.
–Mayr : - According to him similar species are those which are capacble of interbreeding in natureal condtions. Modern definition of species is conied by ''Mayr''.
–Binomial system of Nomenclature was devised by Gesparrd-Bauhin. But the detailed informationabout Binomial system was given by Linnaeus. In 1758 in the 10th edition of his book ''SystemaNaturae'' he gave the classification of known 4236 animals and presented the Binomial system of nomenclature of animal. He is also known as ''Father of Modern-Taxonomy''
–In binomial system the name of each animal has two parts. First part has its genus name and second part has its species name. First letter of genus name must be written in Capital letter and species name is written in small letters eg. Canis familiaris. In certain species, sub-species are also found. For naming the sub species three words are used. First name is for genus, second for species and third for subspecies.The method of nomenclature of Sub-species is termed as the Trinomial nomenclature and it was given by ''Huxley and Strickland''. eg. Homo sapiens sapiens.
– G.L. Cuvier : - Coined the term Phylum.
– Julian-Huxley (1940) : - Proposed New systematic.
– Engler and Prantl : - Proposed Phylogenetic classification.
– Key for identification of animal was developed by John Ray.
–Invertebrate and Vertebrate term was given by Lamarck.
–Robert Whittaker (1969) : - Proposed Five-Kingdom system classification to show phylogenetic relationship.
(1) Monera (2) Protista (3) Fungi (4) Plantae (5) Animalia
– Linnaeus classified animal kingdom into 6-classes.
(1) Mammalia
(2) Aves
(3) Amphibia
(4) Insecta
(5) Pisces
(6) Vermes
SEQUENCE OF CLASSIFICATION :
–Smallest unit of classification is ''Species''. Genus includes various types of species. Family is made up of various genera. Many families join together to form an Order, many order join together to form a class and many classes form a Phylum. All the phyla unite to form the largest unit i.e. Kingdom.
Various grouping levels or ranks in classification known as Obligate categories
–Based on this, all animals are included in the animals kingdom – groups and written in the following Hierarchical manner. For example obligate category of man can be written as
IMPORTANT PHYLA
Storer and Usinger classified whole animal kingdom into 31 phyla. Out of which 10 are major and 21 are minor phyla. Main phyla are :
1. Protozoa - e.g. Amoeba, Paramoecium etc.
2. Porifera - Sponges etc.
3. Coelenterate - Hydra, Jellyfish etc.
4. Ctenophora (minor phylum) - Beroe etc.
5. Platyhelminthes - Tape worm etc.
6. Nemathelminthes-Nematoda - Ascaris etc.
7. Annelida - Earthworm, Leach etc.
8. Arthropoda - Insects, Scorpion, Fly etc.
9. Mollusca - Snail, Pila, Octopus etc
10. Echinodermata - Star fish etc.
11. Hemichordata - Balanoglossus
12. Chordata - Fish, Snake, Birds, Monkey etc.
Basis of Classification
METAZOA :
– Animal groups are characterized by mobility, and the presence of a sensory or a nervous system. These systems receive stimuli from the environment and respond by exhibiting some behaviour.
– The only exception are the porifers (pore-bearers) or the sponges. They have no cell that can be termed as nerve cell.
– Like plant life, early animal life also arose in sea.
– The animals which live on the sea floor are called Benthonic (e.g., echinoderms, corals and deep sea fishes),whereas, which swim about actively in sea are called Nektons.
– The multicellular eukaryotic organisms with holozoic mode of nutrition are called as metazoans.
– Based on complexity of organization, metazoans are further sub-divided into two sub-kingdoms, the Parazoa and Eumetazoa.
–Parazoa : Parazoa includes the sponges in which the cells are loosely aggregated and do not form tissues or organs.
–Eumetazoa : Eumetazoa includes the rest of the animals, the cells are organized into structural and functional units called as tissues, organs and organ systems
SYMMETRY :
–Two type of symmetry are usually seen in the animals :
(i) Radial symmetry :
The animals with radial symmetry are called as Radiata. For example, Cnidarians (hydra, jellyfish and starfish). Biradial symmetry is present in sea anemone.
For sessile animals, radial symmetry is advantageous, as it allows food to be gathered from all sides.
They may develop appendages all round the mouth to capture and push prey into it.
Their sensory and nerve coordination surrounds the mouth. We see this in coelenterates.
(ii) Bilateral symmetry : -
The animals with bilateral symmetry are called as Bilateria. The body can be divided into right and left halves in only one plane.
Bilateral symmetry arose when animals on the ocean floor became mobile.
A crawling animal is most likely to encounter food with the end that goes first. So the mouth developed at this end.
With the mouth, sensory organs and a coordinating brain also development at the front end.
These organs helped in sensing food. So we see how the head, enclosing the brain, became associated with the mouth end. This is cephalization.
Asymmetric organisms cannot be divided in any plane to produce two equivalent halves.
