Diversity In Living Organisms

Biodiversity means the diversity of life forms. It is a word commonly used to refer to the variety of life forms found in a particular region. Diverse life forms share the environment and are affected by each other too. As a result, a stable community of different species comes into together.

• Monera
• Protista
• Fungi
• Plantae
• Animalia
• Thallophytes
• Bryophyta
• Pteridophytes
• Gymnosperms
• Angiosperms
• Porifera
• Coelenterate (Cnidaria)
• Platyhelminthes
• Nematoda
• Annelida
• Arthropoda
• Mollusca
• Echinodermata
• Protochordata
• Vertebrata 
• (i) Cyclostomata
• (ii) Pisces
• (iii) Amphibia
• (iv) Reptilia
• (v) Aves 
• (vi) Mammalia

Monera

These types of Organism do not have a well-defined nucleus or organelle, nor do any of them represent multi-cellular body designs. They also show diversity based on many different characteristics. Some of them have cell walls while others do not. Of course, having or not having a cell well has very different effects on body design. The mode of nutrition in this group can be either by making their own food (autotrophic) or getting it from includes bacteria, blue-green algae (cyanobacteria) and mycoplasma. Some examples are shown in below Fig. 

Protista

This group includes many types of unicellular eukaryotic organisms. Some of such organisms use appendages, such as hair-like cilia or whip-like flagella for moving. Their mode of nutrition may be autotrophic or heterotrophic. Examples are unicellular algae, diatoms and protozoans.

Fungi

These are actually heterotrophic eukaryotic organisms some of them use decaying organic matter as food and are therefore called saprotrophs. Other require a living protoplasm of a host organism for food. They are called parasites. Most of them have the capacity to became multicellular organisms at many stages in their lives. They have cell-walls made of a hard complex sugar called chitin. Examples are yeasts, molds and mushrooms.

Some fungal species live in permanent (mutually dependent) relationships with blue green algae. Such relationships are known as symbiotic. These symbiotic life forms are called lichens. Lichens are the slow growing large colored patched on the bark of trees.

Plantae

These are multicellular eukaryotes with cell walls. They are generally autotrophs and use chlorophyll for photosynthesis. Thus, all plants are considered in this group. As plants and animals are most visible forms of the diversity of life around us. We shall discuss about sub-groups in this category in section.

Animalia

This group includes all organisms which are multicellular eukaryotes without cell walls. They are heterotrophs. Now, we will look at their subgroups in section.

Thallophytes

Plants which do not have well-differentiated body design fall in this group. The plants of this group are called algae. These plants are mainly equating. Examples this group are Spirogyra, Ultrix, Cladophora, Ulva and Chara.

Bryophyta

These are amphibians of the plant kingdom. The plant body is differentiated to form stem and leaf-like structures. But there is specialized tissue for the transportation of water and other substance from one part to another. Examples of this type are Moos (Funaria) and Marchantia.

Pteridophytes

In this class, the plant body is differentiated into roots, stem and leaves and has special tissue for the conduction of water and other substances from one part to another. Examples of this type are Marsilea, ferns and horse- tails. 

The reproductive organs of plants in all three groups are very inconspicuous, and they are called cryptogams' means 'those with hidden reproductive organs.

While plants with-different reproductive parts that finally make seeds are called phanerogams actually, seeds are the result of the sexual reproductive process. They consist of the embryo with stored food, which assists for the initial growth of the embryo during germination. This group is again classified on the basis of the fact that seeds are naked or enclosed in fruits, giving two groups: gymnosperms and angiosperms.  

Gymnosperms

The word gymnosperms is derived from the two Greek word: gymno-means naked and sperm-means seed. This group of plants bears naked seeds and are generally perennial, evergreen and woody. Examples of this group are pines and deodar.

Angiosperms

This term is made from two Greek words: angio means covered and sperma means seed. Plants of this group are also called flowering plants: In this group, the seeds develop inside an ovary which is modified to become a fruit. Plant embryos in seeds have structure called cotyledons. These Cotyledons are called 'seeds leaves' because in many cases they emerge and become green when the seed germinates These angiosperms are classified into two groups on the basis of the number of cotyledons present in the seed. The plants in which seeds have a single cotyledon are called monocotyledonous or monocots and the plants with seeds having two cotyledons are called dicots.

Porifera

This word means organisms with holes. These are non-motile animals attached to solid support. There are holes or 'Pores' present on whole body. These lead to formation of a canal system that helps in circulating water throughout the body to take in food and oxygen. These animals are covered with a hard layer or Skelton. Their body design involves very minute differentiation and division into tissues. These are commonly known as sponges and are found in marine habitats. Some examples are shown in Fig.

 

Coelenterate 

These animals are found in water. These have more body design differentiations. There is a cavity in the 

body. The body is made of two main layers of cells: one which makes up cells on the outer side of the body, and the other which makes the inner lining of the body, some of the species live in colonies (corals), while others have solitary like-span (Hydra). Jellyfish and sea anemones are common examples of this type.

Platyhelminthes

The body of animals of this group is complexly designed than in the two other groups. They body is bilaterally symmetrical, means that the left and the right halves of the body have the same design. These animals are called triploblastic because there are three layers of cells from which differentiated tissues can be made. This allows outside and inside of body linings as well as some organs to the formation of tissue. However, there is no real internal body cavity or coelom, in which well-developed organs can be accommodated. The body is flattened dorsoventrally, (means from top to bottom), that is why these animals are called flatworms. They are either free living or parasitic. Some examples of free-living animals are planarians, or parasitic animals as liver flukes.

Nematoda

The nematode body is also bilaterally symmetrical and trophoblastic. However, this body is cylindrical rather than flattened. Tissues are found there, but no real organs, although a type of body cavity or a pseudo coelom, is found there. These are very familiar as parasitic worms causing diseases, for example, the as parasitic worms causing diseases, for example, the worms causing elephantiasis (filarial warm) or the 

worms in the intestine as roundworms or pinworms. Some examples are given in Fig.

Annelida

The animals are also bilaterally symmetrical and triploblastic, but these have a true body cavity. This allows true organs to be packed in the body structure. Thus, there is extensive organ differentiation. This differentiation takes place in a segmental fashion, with the segments lined up one after are found in number of habitats-fresh water, marine water as well as land. Earthworms and leeches are the examples of these type of animals.

Arthropoda

This group is probably the largest group of animals. These animals are bilaterally symmetrical and segmented. An open circulatory system is found there and so, the blood does not flow in definite blood vessels. The coelomic cavity is full of blood. These have joined legs (the word 'arthropod' means 'jointed legs'). Some examples are prawns, scorpions, butterflies, houseflies, spiders and crabs.

Mollusca

These types of animals have bilateral symmetry. There is little segmentation and coelomic cavity is reduced. These animals have an open circulatory system and kidney-like organs for excretion. These have a foot that is used for moving around. Examples are snails and mussels.

Echinodermata's 

In Greek language, ehino means hedgehog (spiny mammal), and derma means skin. These are spiny skinned and free-living marine animals. These animals are triploblastic and have a coelomic cavity. these also have a peculiar water-driven tube system that is used for moving around. These have hard calcium carbonate structures which are used as a Skelton. Examples of such type are sea-stars and sea urchins.

Protochordata

These animals are mainly bilaterally symmetrical, triploblastic and have a coelom. These show a new feature of body design. called notochord, at some stages during their lives. The notochord is a long rod--like support structure (chord=string) that moves along the back of the animal separating the nervous tissue form the Gutt. It gives a place for muscles to attach for each of movement. Protochordates may not have a proper notochord present at all stages in their lives or for the entire length of the animal. Protochordates are marine examples are balanoglossus, herdemania and amphioxus.

Vertebrata

These animals have a real vertebral column and internal Skelton, having a completely different distribution of muscles for movement.

Vertebrates are bilaterally symmetrical, coelomic, triploblastic and segmented, having complex differentiation of body tissues and organs. All chordates have the following features:

(a) have a notochord

(b) have a dorsal nerve cord

(c) are triploblastic 

(d) are coelmatic

(e) have paired gill pouches Vertebrates are divided into six classes.

(i) Cyclostomata

Cyclostomes are jawless vertebrates. They are characterized by having an elongated eel-like body, circular mouth, slimy skin and are scale less. They are ectoparasites or borers of other vertebrates. Petromyzon (Lamprey) and Myxine (Hagfish) are examples.

(ii) Pisces

These are fish. These are exclusively water-living animals. Their skin is covered with scales or plates. These obtain oxygen dissolved in the water. These breathe thought gills. Their body is streamlined, and a muscular tail is used for movement. These are cold-blooded and have two chambered hearts unlike the four that humans have. These animals lay eggs, for examples, fish, with some skeletons made of cartilages, such as sharks, and some with a Skelton made of both bone and cartilage, such as tuna or rohu fish.

                        

(iii) Amphibia

These types of animals differ from the fish in the lack of scale and in having mucus glands in the skin. These have a three-chambered heart. Respiration occurs through either gills or lungs. These animals lay eggs. These types of animals are found both in water and on land. toads and salamanders are some examples of this type.

(iv) Reptilia

These animals are cold-blooded, having scales and breathe through lungs. Most of these have a three-chambered heart, whereas crocodiles have four heart chambers. These animals lay eggs with tough coverings and do not need to lay eggs in water, unlike amphibians. Snakes, turtles, lizards and crocodiles also fall in this category.

(v) Aves

Aves are warm-blooded animals and have a four-chambered heart. These lay eggs. These animals have an outside covering of feathers, and two forelimbs are used for flight. The animals of this group breathe through lings. All birds count in this category.

(vi) Mammalia

Mammalia are also warm-blooded animals having four-chambered hearts. All mammals have mammary glands for the production of milk to nourish their young ones. their young ones. Their skin is covered with hairs as well as sweat and oil glands. Most mammals produce their young ones/But, a few of these such as platypus and the echidna lay eggs, and some, like kangaroos give birth to poorly developed young ones. Some example are given in Fig. The classification scheme of animals is shown in Fig.