9th Class Science Diversity in Living Organisms Diversity In Living Organisms

Diversity In Living Organisms

Category : 9th Class

Diversity in Living Organisms

Diversity in Living Organism

This world is full of living and non-living things. Large variety of living organisms is found on this planet. There is a great diversity among them. From the microorganisms to well-developed animals, one can notice the diversity at all levels.

Basis of Classification

Classification is a method of arranging organisms into groups or sets on the basis of similarities and differences. The study of classification is known as taxonomy. The process of classification began hundreds of years ago. First animals were classified according to whether they lived on land, in water or in the air, but this classification was not adequate. So the need of more accurate form of classification was realised and thus some characteristics were used as a basis for making the broadest divisions for making groups and subgroups.

Classification and Evolution

All living things are categorised on the basis of their body design the and function. The characteristics that came into existence earlier are likely to be more basic than characteristics that have come into existence later. This clearly indicates that the classification of life forms is directly and very closely related to the evolution. Charles Darvin the renowned biologist first described the idea of evolution in 1859 in his book

"The Origin of Species".

Hierarchy of Classification

H. Whittaker in 1969 proposed five kingdom classification. They are as following:

Five Kingdom Classification

Characters	Monera	Protista	Fungi	Plantae	Animalia
Cell type	Prokaryotic	Eukaryotic	Eukaryotic	Eukaryotic	Eukaryotic
Cell wall	Noncellular (Polysaccharide +amino acid)	Present in some	Present (without cellulose)	Present (cellulose)	Absent
Nuclear membrane	Absent	Present	Present	Present	Present
Body organisation	Cellular	Cellular	Multiceullar/ loose tissue	Tissue/Organ	Tissue/Organ/organ system
Mode of nutrition	Autotrophic (Chemosyn-thetic and photosynthetic) and Hetero-trophic (sapro-phyte/para-site)	Autotrophic (Photosyn-thetic)and Hetero-trophic	Heterotrophic (Saprophytic/ Parasitic)	Autotrophic (Photosyn- thetic)	Heterotrophic/ Saprophytic etc.

Monera: The organisms that come in this category do not have a defined nucleus or organells. They do not show multicellular body design. The mode of nutrition in these organisms can be either autotrophic or heterotrophic. The organisms of this group are bacteria, blue-green algae, etc.

Protista: It consists of unicellular eukaryotic organisms. Some of these organisms use appendages such as hair like cilia or whip like flagellum. Their mode of nutrition can be autotrophic or heterotrophic. The organisms of this group are unicellular algae. protozoan amoeba, etc.

Fungi: They are the heterotrophic and eukaryotic organisms. They may be unicellular or multicellular. They have a cell wall containing a mixture of chitin and cellulose. They use decaying organic material as food and are therefore, called saprophytes. The organisms of this group are yeast, mushroom, rhizopus, etc.

Plantae: They are the multicellular eukaryotes with cell walls. Their mode of nutrition is autotrophic and they use chlorophyll for photosynthesis. Plantae can be further classifies in the following types:

Examples:

Thallophyta Bryophyta Pteriophyta

Chara Ricca Equisetum

Gymnosperms

Ginkgo Conifer

Angiosperms

Monocotyledon Wheat Dicotylendon: mango

Animalia: They are multicellular, eukaryotic organisms without cell walls. The mode of nutrition is heterotrophic. Their cells do not have cell walls and most of the animals are mobile. They are classified into the following groups:

Kingdom Animalia

Phylums and Their Characteristics

PHYLUM	CHARACTERISTICS	EXAMPLES
Porifera	· They are non-motile organisms. · The body has many pores. · Body is covered with hard outer skeleton. · They can reproduce sexually as well as asexually.	Sycon, Euplectella, Euspongia, Spontilla, etc.
Coelenterata (Cnideria)	· The body has tissue level of organization. · They are diploblastic animals. · The mouth is surrounded by ring of tentacles. · They can reproduce sexually as well as asexually.	Hydra, Jelly fish, Sea anemone, Aurelia, etc,
Platyhelminthes	· They are first triploblastic animals. · They possess a mouth but not anus. · The body is bilaterally symmetrical. · Reproduction takes place mostly sexually but few reproduces asexually.	Planaria, Tapeworm, Liver fluke, Blood fluke, etc.
Nematoda	· The body has tissue level of organization. · They are triploblastic, bilaterally symmetrical and unsegmented animals. · The internal organ lie in a pseudocoelom. · Most of them are free living.	Ascaris,Enteribius, Hookworms, Pinworms, etc.
Annelida	· They are triploblastic and contain true colelom. · They are elongated, segmented, worm-like animals. · The body is bilaterally symmentrical and have organ level of organization. · They reproduces sexually.	Earthworm, Leeches, Clamworms, Sea mouse, etc.
Arthropoda	· The body is bilaterally symmetrical and segmented. · They are triploblastic and possess true coelom, · The body can be differentiated into three regions: head, thorax and abdomen. · They reproduces sexually.	Prawn, Crab, Housefly. Cockroach, etc.
Mollusca	· They are triploblastic and possess true coelom. · The body is bilaterally symmetrical. · The body is unsegmented or with little segmentation and soft. Little segmentation and soft · The body is often protected by a hard calcareous shell.	Sea urchin, Starfish, Antedon, Sea cucumber, etc.
Chordata	· They are triploblastic animals. · They have bilaterally symmetrical body. · They have true vertebral column and internal skeleton. · They have complex differentiation of body tissues and organs.	Fish, Crocodile, Crow, Frog, Man, etc.

The phylum chordate have been further divided into three subphylum such as: eurochordata, cephalochordate and vertebrata.
The subphylum vertebrata has mainly five classes and these are as follows:

CLASS	CHARACTERISTICS	EXAMPLES
Cyclostomata	· They are the most primitive vertebrates. · They are animals with cartilaginous endoskeleton. · The circulatory system includes a two chambered heart. · Their gills are enclosed in pouch.	Lampreys, Hagfish, etc.
Chondrichthyes	· Their skeleton is made of cartilage. · They are mostly marine. · Their gills are not covered by an operculum. · They are unisexual and fertilization is internal.	Shark, Sting rays, Electric rays, Dogfish, etc.
Osteichthyes	· They have skeleton of bones. · Their gills are covered by an operculum. · In most of the animals external fertilization takes place. · Their fins are membranous.	Slamon, Sea horse, Trout, Carp, etc.
Amphibia	· They can live in water and on land. · They are cold-blooded animals. · Respiration takes place through gills or lungs. · Heart is three-chambered.	Toad, Frog, Salamander, etc.
Reptilia	· They are cold-blooded animals. · They have lungs for breathing and respiration. · Most of them have three chambered heart. (Except crocodile which has four chambered heart)	Tortoise, Snake, Chameleon Crocodile, etc.
Aves	· They have feathers and body is covered with scales. · They are warm-blooded animals. · Heart is four chambered. · They have lungs for respiration.	Pigeon, Crow, Ostrich, Penguin, etc.
Mammalia	· They possess mammary glands. · The body is covered with hairs. · They are warm-blooded. · They give birth to young ones. (Except platypus and echidna) · Heart is four ? chambered.	Humans, Rat, Dog, Elephant, etc.

9th Class Science Diversity in Living Organisms Diversity In Living Organisms

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