Diversity in Living Organisms

 

DIVERSITY IN LIVING ORGANISMS

 Introduction

There are large variety of living organism in this world and each organism is unique in its own way. This uniqueness of each organism is called diversity.

Due to large diversity it is necessary to classify the organisms. The biological science which deals with the identification, naming and classification of organism is called Taxonomy. In science we normally follow binomial nomenclature i.e. each organism is given two name, the first name is called genus and the second name is called species. The genus represents the community to which the organism belongs and the second name represents specific organism to which it belongs. Linnaeus is considered to be the father of taxonomy as he developed the binomial system of nomenclature. The scientific name of some of the common organisms are given below:

SL. No.	Common Name	Scientific Name
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.	Lion Tiger Dog Cat Rat Mango Neem Potato Lotus Honey Bee Ant Peacock	Panther Leo Pinthra Tigress Canis Lupus Felis Catus Tattus Norvegicus Mangifera Indica Azadirachta Indica Solanum Tuberosum Nelumbo Nucifera Apis Mellifera Formicidae Pavo Cristatus

      Classification of Organisms

Since there is one or the other similarity and dissimilarity among the organisms and. also there are large number of organisms in this world and it is very difficult to identify and understand each of them separately. Hence we need to classify the organisms. The main advantage of classification of organism is that it makes the study of large variety of organism easier. It also tells us the interrelationship among the various organisms. In ancient times the classification was based on some basic criteria such as size, colour, and nature of the organism. Later on the system of classification was based on overall similarities and dissimilarities between the organisms.

In present time the organisms has been classified into two groups as plant Kingdom and animal kingdom. The main difference between plant kingdom and animal kingdom is that plant can manufacture their own food using sunlight and carbon dioxide, where as the animals derive its food from the plants. Later on it was found that there were some organism which fit into neither plants nor animals category. Hence the classification system was further modified.

At present time there are five kingdom of classification:

• Monera
• Protista
• Fungi
• Plant
• Animal

           Hierarchy of Classification

The five kingdom of classification given by Whittaker was based on the cell structure of the organism, mode of nutrition and their body design. The classification is done by naming the subgroups at various level as:→

 Kingdom Phylum →Class →Order →Family →Genus → Species

In broadest mode of classification the organisms has been classified into two categories as plant kingdom and animal kingdom. The next step is the phylum which includes all the organism having few common characters. The next is  the mammals. Mammal is followed by order which includes the organism having few common character and are less similar, such as carnivorous and omnivorous. The next step is the family which includes the group having more similarity to each other, such as, the family of cat and lion is similar. The next is genus, which includes the organisms having similar reproductive organs, such as, plants producing flower and fruits. The last step is the species which include the group of organism having same structure and forms, but not necessarily the function and are able to breed among themselves and produce the fertile offspring of their own kind.

                                Different Kingdoms of Organisms  

                Monera

These are basically the unicellular organism which do not have well defined nucleus and nor have any cell organelles. Some of these organisms have cell wall while other do not. They are either autotrophic or heterotrophic in nature. For example, the organism like blue green algae, halophiles, cocci, bacilli and spirilla.

                Protista

This kingdom includes many kinds of unicellular eukaryotic organisms which uses appendages such as cilia and flagella for movement from one place to another. They are either autotrophic or heterotrophic. Most of them are aquatic in nature having irregular body design. Cytoplasm is divided into two parts, outer and inner parts. They reproduce either by sexual or asexual. For example, the organism like algae, diatoms and protozoa comes in this categories.

Fungi

Fungi are the non-green plants that are heterotrophic in nature. Some fungi are parasitic in nature and derive its food from the other organisms. For example, albugo, ustilago etc. Some others are saprophytic in nature. For example, Rhizopus, Agaricus etc. They are either unicellular or multicellular. Their cell wall is made up of chitin and cellulose and stores food in the form of glycogen. Some algae such as blue green algae, shows symbiotic relationship among them self and are also called lichens. The lichens are the green patches which grows on the rocks, and watery area around the drains and barks of the trees. The fungus absorbs water and minerals from the soil and supplies it to the algae which in turns prepare food and supplies it to the fungus.

Plant

These are the multicellular organisms which are autotrophic in nature. The plants are further subclassified into three subgroups such as Thallophyta, Bryophyte, and Pteridophyte. The first basis of classification is that whether the plant body has well differentiated body parts or not. The second basis of classification is wether the parts of the plant's body have special tissues for transportation of water and mineral or not. The third basis of classification is, if the plant produces seeds and fruits or not. We will discuss each of them in 

                Thallophyta

This group includes the most primitive plants which do not have well differentiated body design. The body cannot be differentiated into stem, roots and leaves and is in the form of undivided body, called thallus. These groups commonly includes algae which are aquatic in nature and are founded in both fresh water and marine water. They contains the pigments called chlorophyll which helps them in photosynthesis and hence they are autotrophic in nature. They have cell wall around their cell and do not have any conducting tissue. They generally reproduce by spore formation.

            Bryophyte

These are multicellular plants founded in the damp places and are called amphibians. Its body can be differentiated into stem and leaf. It does not possess any specialized tissue, such as xylem and phloem, for conduction of water and mineral from one part to the another. For example Riccia, Marchantia, Funaria and Barbula.

           Pteridophyta

This group includes the plants whose bodies can be differentiated into roots, stem and leaves. It contains the specialized tissue for conduction of water and mineral from one part of the plants to the other parts. They do produce seeds and flowers. They have well developed reproductive tissue which produce seeds and are called phanerogams. These groups are further classified on the basis of naked seeds or closed seeds. These two groups are gymnosperm and angiosperms.

The gymnosperms includes the plant having naked seeds and are normally perennial, evergreen and woody. For example pinus, cycas, deodar, etc  

The angiosperms includes the covered seeds which are developed inside an organ and is modified to becomes fruits. They are flowering plants. The seeds have structure called cotyledons. The angiosperms is divided into two groups on the basis of cotyledons presents in the seeds as monocotyledons and dicotyledons. The plants having single cotyledons in the seeds is called monocotyledons, such as maize, wheat, rice, sugarcane, barley, etc are the example of monocotyledons.

The other one is the plant having two cotyledons in the seeds and are called dicotyledons. For example pea, rose, sunflower, apple, grams etc.

   Animalia

These organisms are multicellular and heterotrophic. Most of them can move from one place to another and lacks ceil wall in their cell. They are further classified on the basis of body design and cell structures. Some of the phylum of the animal kingdom are discussed below

            Porifera

These organisms have smallest holes on their bodies and are non motile in nature. These small holes on their bodies forms the canal system in the body and helps in circulating water, oxygen, and food. They have hard outer covering on their body and are mainly founded in marine water. They are multicellular and diploblastic which have radial symmetry. They do not have any well developed organs like mouth, body cavity, and anus.

              Coelenterata

They are multicellular and diploblastic animals having more organized tissue structure. Their body shows radial symmetry and are mostly founded in marine water, except for few, such as. Hydra. They have only cells of nervous system and can reproduce by both sexual and asexual methods. They possess central

gastrovascular cavity which consist of mouth surrounded by short and slender tentacles. Some of them live in colonies while other live independently. For example the jelly fish and Hydra shows independent existence.

           Platyhelminthes

Their bodies shows bilateral symmetry and dorsoventrally flattened animals. Their bodies are triploblastic and have digestive cavity with a single opening called mouth. They have suckers for taking food and hooks for movements.

They do not have any circulatory system. They are either free living or parasitic in nature. For example, planaria are free living and liver flukes are parasitic in nature. They are also hermaphrodite i.e. both the sex male and female are present in the same individuals. They do not have true internal body cavity.

             Nematoda

Their bodies shows bilateral symmetry and are triploblastic. Their bodies have tissues and have true body cavity, but no real organs. The body is covered with tough resistant cuticle that provides their bodies some sorts of shape and structure. Male and female are found in different individuals. Most of them are parasitic, but very few are free living. For example round worm, filarial worms are parasitic in nature.

             Anneelida

These organisms show bilateral symmetry and are triploblastic. They also have true body cavity. The body is covered with thin cuticles and have lateral appendages for locomotion. They have alimentary canal in the form of tube like structure which extends from mouth to anus. They have nephridia for removal of waste and nervous system consists of dorsal brain and a ventral nerve chord having ganglia and lateral nerve in each segment of the body. They are either aquatic or terrestrial. For example earth worms and leeches.

           Arthropoda

The body of the organism is bilaterally symmetrical and are triploblastic. The body is divided into two parts, head and thorax. The head part consists of brains, and sense organs. They have open circulatory system and hence blood does not flow in a well defined blood vessels. The male and female sex are usually different and shows internal fertilization. They are free living or parasitic in nature. They are the largest phylum of the animal kingdom. For example housefly, spider, butterfly, cockroach, etc.

            Mollusca

These organisms have bilateral symmetry with little segmentation on their body. They have open circulatory system and have kidney like organ for excretion and have foot for movement. They respires by gills and have sensory organ of touch, smell, vision, and taste. The male and female are in different organisms and are mostly aquatic in nature. For example , etc.

             Echinodermata

These organisms have radial symmetry and are triploblastic and unsegmented body. They have spines on their skins and are free-living marine animals. They have complete digestive system and excretory system is absent. They reproduce by both sexual and asexual mode. Some of them even reproduce by regeneration. Male and female are on different organisms. They have hard outer covering made up of calcium carbonate. For example starfish and antedon.

             Protochordata

These organisms are bilaterally symmetrical, triploblastic and coelom. They have bag like soft bodies. They have notochord in their bodies having dorsal tubular nerve chord. They are hermaphrodite and are exclusively marine animals. Adult have cellulose covering over their bodies.

             Vertebrate

The vertebrate have true vertebral column and internal skeleton which provides them a definite body design. They are bilaterally symmetrical, triploblastic and have segmented body. They have notochord and a dorsal nerve chord. They have pair of gill pouches. The vertebrated are further classified into five

groups as pisces, amphibia, reptilia, aves, and mammals.

(A) Pisces: These are fishes and are exclusively aquatic animals with their skins covered with scales. They obtained oxygen dissolved in water using gills. They have streamlined body and muscular tails which is used for movement. They are cold blooded animals and hearts is two chambered. They reproduce by lying eggs. The skeletons is entirely made up of cartilage tissue. The digestive system is with J -shaped stomach and intestine with spiral valves. They have well developed sense of smell, vibration reception and electro reception. Their size varies from few mm to several meters.

(B) Amphibia: The amphibians are the groups of animals having chordates which lives on land as well as in water. They have three chambered heart and respire through gills or lungs. They reproduce by laying eggs i.e. oviparous and fertilization is external in case of frogs and toads, but internal in salamanders and apoda. They have mucus gland in the skin and are cold blooded animals. They have two pairs of pentadactyl.  

(C) Reptilia: The reptials are the cold blooded animals having scales on their skins and breaths through lungs. Most of them have three chambered heart, but few of them like crocodiles have four chambered heart. They have two pairs of limbs with pentadactyl and respires through lungs. Teeth are present in almost all of them. They reproduce through internal fertilization and most of them lay eggs i.e. oviparous, but few reptiles are viviparous like lizard and snakes.

(D) Aves: The aves are the warm blooded animals with four chambered heart. Their body is covered with feathers and two forelimbs is modified into wings which helps them in flight. They respires through lungs. Bone have air cavity and hence are light which helps them to fly. Body is divided into head, neck, trunk and tail. They are oviparous and reproduce by laying eggs. The fertilization is internal.

  (E) Mammalia: The mammals are warm blooded animals having four chambered heart and breath through lungs. They are viviparous and are breast feeding to their young ones. They have sweat gland on their body and also have hair on their skins. They have external ear which helps them

to hear sounds from the surroundings. They have two pairs of pentadactyl limbs which are variously adapted for walking and running. They respires through lungs. They have internal fertilization and penis is always present. The parents take care of their young one.

 

BY MONIKANARANG