IX Bio SS-2 (Diversity in Living Organisms )
IX Bio SS-2 (Diversity in Living Organisms )
Diversity in Living Organism
CLASSIFICATION
Biodiversity: The variety of living beings found in geographical area is called biodiversity of that area. Amazon rainforests is the largest biodiversity hotspot in the world.
Need for Classification: Classification is necessary for easier study of living beings. Without proper classification, it would be impossible to study millions of organisms which exist on this earth.
Basis of Classification:
Ancient Greek thinker Aristotle classified living beings on the basis of their habitat. He classified them into two groups, i.e. those living in water and those living on land. But his classification was too simple to justify inclusion of a particular organism into a particular group.
Some examples of scientific bases of classification are as follows:
Organization of nucleus: Nucleus may or may not be organized in an organism. On this basis, organisms can be divided into two groups, viz. prokaryotes and eukaryotes.
(a) Prokaryotes: When nucleus is not organized, i.e. nuclear materials are not membrane bound; the organism is called prokaryote.
(b) Eukaryotes: When nucleus is organized, i.e. nuclear materials are membrane bound; the organism is called eukaryote.
Number of cells: An organism can be composed of a single cell or many cells. An organism with a single cell is called unicellular organism. On the other hand, an organism with more than one cell is called multicellular organism.
Mode of Nutrition: On this basis, organisms can be divided into two broad groups, i.e. autotrophs and heterotrophs. An autotroph makes its own food, while a heterotroph depends on other organisms for food.
Level of Organisation: Even in case of multicellular organisms, there can be different levels of organization. When a cell is responsible for all the life processes, it is called cellular level or organization. When some cells group together to perform specific function, it is called tissue level of organization. When tissues group together to form some organs, it is called organ level of organization. Similarly organ system level of organization is seen in complex organisms.
Classification and Evolution: It is a well established fact that all the life forms have evolved from a common ancestor. Scientists have proved that the life begun on the earth in the form of simple life forms. During the course of time, complex organism evolved from them. So, classification is also based on evolution. A simple organism is considered to be primitive while a complex organism is considered to be advanced.
Five Kingdom Classification by Robert Whittaker (1959)
This is the most accepted system of classification. The five kingdoms and their key characteristics are given below:
1. Monera: These are prokaryotes; which means nuclear materials are not membrane bound in them. They may or may not have cell wall. They can be autotrophic or heterotrophic. All organisms of this kingdom are unicellular. Examples: bacteria, blue green algae (cyanobacteria) and mycoplasma.
2. Protista: These are eukaryotes and unicellular. Some organisms use cilia or flagella for locomotion. They can be autotrophic or heterotrophic. Examples: unicellular algae, diatoms and protozoans.
3. Fungi: These are heterotrohic and have cell wall. The cell wall is made of chitin. Most of the fungi are unicellular. Many of them have the capacity to become multicellular at certain stage in life. They feed on decaying organic materials. Such a mode of nutrition is called saprophytic. Some fungi live in symbiotic relationship with other organisms, while some are parasites as well. Examples: yeast, penicillum, aspergillus, mucor, etc.
4. Plantae: These are multicellular and autotrophs. Presence of chlorophyll is a distinct characteristic of plants, because of which they are capable of doing photosynthesis. Cell wall is present.
5. Animalia: These are multicellular and heterotophs. Cell wall is absent.
Kingdom Plantae:
The Plant Kingdom can be further classified into five divisions. Their key characteristics are given below:
1. Thallophyta:- The plant body is simple thallus type. The plant body is not differentiated into root, stem and leaves. They are commonly known as algae. Examples: Spirogyra, chara, volvox, ulothtrix, etc.
2. Bryophyta:- Plant body is differentiated into stem and leaf like structure. Vascular system is absent, which means there is no specialized tissue for transportation of water, minerals and food. Bryophytes are also known as the amphibians of the plant kingdom, because they need water to complete a part of their life cycle. Examples: Moss, marchantia.
3. Pteridophyta:- Plant body is differentiated into root, stem and leaf. Vascular system is present. They do not bear seeds and hence are called cryptogams. Plants of rest of the divisions bear seeds and hence are called phanerogams. Examples: Marsilear, ferns, horse tails, etc.
4. Gymnosperms:- They bear seeds. Seeds are naked, i.e. are not covered. The word ‘gymnos’ means naked and ‘sperma’ means seed. They are perennial plants. Examples: Pine, cycas, deodar, etc.
5. Angiosperms:- The seeds are covered. The word ‘angios’ means covered. There is great diversity in species of angiosperm. Angiosperms are also known as flowering plants, because flower is a specialized organ meant for reproduction. Angiosperms are further divided into two groups, viz. monocotyledonous and dicotyledonous.
(a) Monocotyledonous: There is single seed leaf in a seed. A seed leaf is a baby plant. Examples: wheat, rice, maize, etc.
(b) Dicotyledonous: There are two cotyledons in a seed. Examples: Mustard, gram, mango, etc.
Kingdom Animalia:-
The animal kingdom is classified into different phyla. Their detail is given below:
1. Porifera: These animals have pores all over their body. The pores lead into the canal system. Water flows through the canal system and facilitates entry of food and exchange of other materials. The animal is not differentiated into tissues. The body is covered with a hard outer skeleton. These are commonly known as sponges. They are marine animals. Examples: Sycon, spongilla, euplectelea, etc.
2. Coelenterata: The body is made up of a coelom (cavity) with a single opening. The body wall is made up of two layers of cells (diploblastic). Some of the species live a solitary life while others live in colonies. Examples: Hydra, Jelly fish, Sea anemone, etc.
3. Platyhelminthes: The body is flattened from top to bottom and hence the name platyhelminthes. These are commonly known as flatworms. The body wall is composed of three layers of cells (triploblastic). Because of three layers, it is possible to form some organs as well. But a proper ceolom is absent in platyhelminthes and hence proper organs are absent. They are free-living or parasitic animals. Examples: Planaria, liver fluke, tapeworm, etc.
4. Nematohelminthes: The body is bilaterally symmetric and there are three layers in the body wall. Animals are cylindrical in shape. A pseudocoelom is present and hence organs are absent. Examples: Roundworms, pinworms, filarial parasite (Wuchereria), etc.
5. Annelida: True body cavity is present in these animals. The body is divided into segments and hence the name annelida. Each segment is lined one after another and contains a set of organs. Examples: Earthworm, leech, etc.
6. Arthropoda: Animals have jointed appendages which gives the name arthropoda. Exoskeleton is present which is made of chitin. This is the largest group of animals; in terms of number of species. Circulatory system is open, which means blood flows in the coelomic cavity. Examples: cockroach, housefly, spider, prawn, scorpion, etc.
7. Mollusca: The animal has soft body; which is enclosed in a hard shell. The shell is made of calcium carbonate. Circulatory system is open and kidney like organ is present for excretion. The body has well developed muscular feet for locomotion. Examples: Snail, mussels, octopus, etc.
8. Echinodermata: The body is covered with spines, which gives the name echinodermata. Body is radially symmetrical. The animals have well developed water canal system, which is used for locomotion. Skeleton is made of calcium carbonate. Examples: Starfish, sea urchins, etc.
9. Protochordata: Animals are bilaterally symmetrical, triploblastic and ceolomate. Notochord is present at least at some stages of life. Notochord is a long rod-like structure which runs along the back of the animal. This provides attachment points for muscles. It also separates the nervous tissues from the gut. Examples: Balanoglossus, herdmania, amphioxus, etc.
10. Chordata: Animals have notochord, pharyngeal gill slits and post anal tail; for at least some stages of life. Phylum chordata is divided into many sub-phyla; out of which we shall focus on vertebrata.
Vertebrata:
The notochord is replaced by a spinal column during embryonic stage. Following are the main characteristics of vertebrates.
- Notochord present; which is replaced by spinal column.
- Dorsal nerve chord is present.
- Animals are triploblastic and coelomate.
- Animals have paired gill pouches.
Vertebrates are divided into two super classes, viz. pisces and tetrapoda.
A. Pisces: They are commonly known as fish. The body is streamlined. Muscular tail is present which assists in locomotion. Body is covered with scales. Paired gills are present; which can breathe oxygen dissolved in water. They are cold-blooded animals. The heart has only two chambers. They lay eggs. Fishes can be bony or cartilaginous. Shark is an example of cartilaginous fish. Rohu and katla are examples of bony fish.
B. Tetrapoda: Animals have four limbs for locomotion and hence the name tetrapoda. Tetrapoda is divided into four classes, viz. amphibia, reptilia, aves and mammalia.
(1) Amphibia: These animals are adapted to live both in water and land. Mucus glands on skin keep the skin moist. The animals breathe through skin when in water and through lungs when on land. The heart has three chambers. These are cold blooded animals. Examples: Frog, toad, salamander, etc.
(2) Reptilia: These animals show crawling movement for locomotion. Skin is hardened to form scales. Most of the reptilians have three chambered heart but crocodile has four-chambered heart. They don’t need water to lay eggs, rather eggs are covered with hard shells and laid on land. Examples: snakes, lizards, crocodile, turtle, etc.
(3) Aves: The body is covered with feathers. Forelimbs are modified into wings. These are warm-blooded animals. The heart has four chambers. Bones are hollow (pneumatic); which assists in flying. All the birds belong to this class.
(4) Mammalia: The body is covered with hairs. Skin has seat glands and sebaceous glands. Mammary glands are present in females and are used for nourishing the young ones. Most of the mammalians give birth to young ones and are called viviparous. Some of the mammals lay eggs and are called oviparous. Examples: human, chimpanzee, lion, platypus, horse, etc.
Binomial Nomenclature of Organisms:
The system of binomial nomenclature was proposed by Carolus Linneaus (1707 – 1778). Conventions of writing biological name are as follows:
- The biological name is composed of two terms. The first term is called genetic name and the second term is called species name.
- The genus name starts with a capital letter, while the species name starts with a small letter.
- In print, the scientific name is written in italics.
- When handwritten, the genus name and species name need to be underlined separately.
DIVERSITY IN LIVING ORGANISMS BIOLOGY
CLASSIFICATION: - Classification of organisms may be defined as a system of arrangement of organisms into different groups and sub-groups on the basis of their similarities, differences and relationship.
Classification of organisms is also known as taxonomy. It has the following advantages.
1. Classification makes the study of a wide variety of organisms convenient and easy.
2. It is not possible for man to know about all the organisms but the study of a few representatives from each taxonomic group gives a general idea of all life forms at a glance.
3. Classification also reveals the interrelationship among different gr4oups of organisms.
4. Correct identification of an organism and its placement in a definite taxonomic group is the basic requirement of various branches of biological sciences. Thus, classification of organisms provides a base for the development of other biological sciences.
BASIS OF CLASSIFICATION:-Classification can be done on the following basis.
1. Cells are prokaryotic or eukaryotic. Organisms may be grouped into two broad categories on the basis whether they possess prokaryotic cells or eukaryotic cells. In case of prokaryotic cells the nuclei and other organelles are not clearly demarcated. The eukaryotic cells, on the other hand, have membrane-bound organelles, including a nucleus.
2. Cells occur singly or in clusters. Many organisms are unicellular, i.e. made up of only one cell, e.g. Amoeba. Others are multicellular, i.e., cells group together to form single organism (e.g., insect). In case of multicellular organisms the different groups of cells carry out specialized functions
3. Organism is photosynthetic or takes food from outside. Green plants perform photosynthesis an synthesis their own food. Animals cannot perform photosynthesis. They get food from outside.
4. Organization of different body parts. Grouping of organisms may be done on the basis of body organization. For example, plants possess stem, root and leaves. Similarly, the animals possess specialized organs to perform different function. The characteristic based on body design used for classification of plants is quite different when used for classifying animals.
Systems of classification:-
R H whittaker in 1969, suggested five kingdom classification on the basis ofr (i) preence or absence of a nucleus (ii) unicells or multicells and (iii) mode of nutrition.
He proposed five kingdoms:
1. Monera, 2. Protista, 3. Fungi, 4. Plantae and 5. Animalia.
Monera: - these organisms do not have a defined nucleus or organelles, nor do any of them show multi-cellullar body designs. They show diversity based on many other characteristics. Some of organisms of this group are either autotrophic or heterotrophic. This group includes bacteria, blue-green algae or cynobacteria and mycoplasma.
Protista:- This group includes many kinds of unicellular eukaryotic organisms. Some of these organisms use cilia or flagella for moving around. Their mode of nutrition can be autotrophic or heterotrophic. Examples are unicellular algae, diatoms and protozoans.
Fungi:- these are heterotrophic eukaryotic organisms. They are saprophytes and thrive on decaying organic material. They have cell-walls made of chitin. Examples are yeast and mushrooms.
Plantae:- these are multi-cellular eukaryotes with cell walls. They are autotrophs and used chlorophyll for photosynthesis. All plants are included in this group. Animalia:- these includes all multi-cellular organisms. They are heterotrophs. NOMENCLATURE:-
Naming a correct scientific name to an organism or a taxon is called nomenclature. It involves the principals governed by set rules formulated by internationals bodies so that a particular organism or taxon is known by its specific name throughout the world.
BINOMIAL NOMENCLATURE:-
According to the binomial system of nomenclature, the scientific name of an organism consist of two separate components – first on designates the genus (generic name) and the second one designates the species (specific name). For example, the scientific binomial name of human species is Homosapiens, where first name Homo is generic and the second name sapiens is a specific. Homo sapiens are understood to mean humans all over the world. Since this system of naming organisms gives two names to an organism, it is known as a binomial nomenclature.
Various ranks used in classification (Hierarchy of classification).
In classification, the organisms that closely resemble one another are placed in a group. These groups are further placed in large groups on the basis of close similarities. The larger groups are again placed in still larger grouping levels or ranks in classification are known as categories. Each category has its specific name. There are seven major categories:
1. Species 2. Genus 3. Family 4. Order 5. Class 6. Phylum (for animals)/division (for plants) 7
Kingdom.
1. Species. Species is the lowest category regarded as basic unit classification. It is a group of similar individuals which resembles with each other in morphology, breed among themselves but not with others and probably descended from a common ancestor.
2. Genus. A genus is a group of closely resembling species having a common ancestry. A;; the species in a genus show similarities in broad features of their organization but differ in minor details.
3. Family. A family represents a larger group of closely related genera. It is composed of one or more genera.
4. Oder. An order is a group of closely related families. 5. Class. A class is a group of related orders.
6. Phylum/Division. Phylum (in case of animals) or Division (in case of plants) is a group of related classes.
7. Kingdom. Kingdom is the highest category in biological classification. It is group of phyla (in case of animals) or divisions (in case of plants).
Mainly, the following rules apply to scientific names:
They were initially framed by Linnzeus. And were revised in 9th and 20th century through international code of Botinical Nomenclature (ICBN) and international code of Zoological nomenclature (ICZN). They are as followes:
1. Each organisms has a distinct scientific name having a words, generic and scientific.
2. The generic and specific words should not have less then three letters or more than 12(twelve) letters.
3. The generic name is written first. It is like a noun . Is first letter is always capital.
4. The specific word is written after the generic name, It starts with small letter. 5. The name of the discoverer is appended to the two-word scientific name either
In full or abbreviate form e.g., mangifera indic . L(L stands for Linnaeus). 6. Scientific name is printed in italics hand written name is underlined.
7. When an organism has been given different scientific names by different workers the “law of priority” is followed that is old valid name is accepted and others rejected.
KINGDOM PLANTAE:-
Characteristics features of kingdom plantae. i) They are made of eukaryotic cells.
ii) They are multicellular.
iii) The cells have wall made of cellulose.
iv) They store carbohydrates such as starch.
v) Some cells (except in some parasites) contain chloroplast. vi) The organisms feed by photosynthesis.
PLANT KINGDOM
According to the classification proposed by eicher, plant kingdom is divided in to two subkingdoms i.e crypotogamae and phanerogamae.
_CRYTOGAMAE:- These are known as lower plants. The flower/seed are absent and hence these are considered to have hidden reproductive organs. It is categorized into 3 divisions.
1).THALLOPHYTA:- Thallophytes have a body which is not differentiated into stem, root and leaves. This kind of undifferentiated body is called thallus, hence the name thallophytes.
It has the following characteristics.
(1) The plant body is thalloid i.e., cannot be differentiated into stem, root and leaves.
(2) The vascular system is absent in such plants.
(3) The reproductive organs are single called and there is no embryo formation.
Thallophyta is further subdivided into: (A) Algae
(B)Fungi (C)Lichens
(A) ALGAE : They generally include aquatic plants. Some 20,000species of algae are known. The main characteristics are as under :
1. They are generally chorophyllous thallophytes in which vascular tissues are absent.
2. The plant body is thalloid i.e., cannot be differentiated into root, stem and leaves.
3. They are found in fresh water resources as well as in sea water.
4. They are autotrophic because of the presence of chlorophyll in leaves. The reserve food is generally a carbohydrate.
5. The cell wall is double layered. The outer layer is made of pectin and inner layer is made cellulose.
6. They may be unicellular as well as multicellular.
7. A few members such as chlamydomonas are motile.
8. They reproduce by vegetative, asexual as well as sexual methods. The sex organs are unicelled and lack a sterile covering around them.
Example : oedogonium, Chara, Sargassum, Ectocarpus, Chlamydomonas, Ulothrix etc.
(B)FUNGI : it is a large group of over 90,000 species. They show the following characteristics :
1. They are achlorophyllous and nonvascular plants.
2. The plant body may be unicelled or vthalloid, made of branched or unbranched filamentous structures, the hyphae.
3. The network of hypae is called mycelium.
4. The hyphae may be aseptate or sepate and each cell may be uni-or multinucleale.
5. The cell wall is made of chitin or fungal cellulose. 6. They show heterotrophic mode of nutrition.
7. The reserved food is in the form of glycogen and oil globules. 8. They reproduce by asexual or sexual methods.
9. The sex organs are unicelled and lack a sterile covering around them. The higher forms lack distinct sex organs.
Example : Rhizopus, Yeast, Agaricus (Mushroom) etc.
(C) LICHENS : They represent a symbiotic association of a fungus and a alga in which two organisms are so closely associated with each other as to form a single plant. They are show growing long lived plants. The commonly grow on leaves, tree trunks, old logs, soils and rocks. Some lichens occur in extreme conditions of cold, humidity and drought.
In these plants the algal part prepares the food and the fungal part shows reproduction. Thus, their association is mutualistic.
2). BRYOPHYTA:- Bryophytes are simple terrestrial plants
They have over 25,000 species. They show the following characteristics:-
1. They lice in damp and sandy habitates hence they are called amphibians of the plant kingdom. They are aften found to grow during rainy season forming green carpets or mats on damp soil, rocks, walls, tree trunks etc.
2. The vascular tissues are absent.
3. The roots are absent and instead rhizoids are present. They may be unicellular or multicellular.
4. The reproduction takes place by vegetative or sexual methods.
5. The vegetative reproduction is quite common through fragmentation tubes, gemmae, buds, adventitions branches etc.
6. They show distinct alternation of generation. Example: Riccia, Marchantia, Funaria (Moss).
(iii). PTERIODOPHYTA: - These are the oldest vascular plants this includes the forms. The important characteristics are
1. The plant body is differentiated into roots, stem, and leaves. 2. The dominant phase or plant body is a sporophyte.
3. They are seedless vascular plants and hence called vascular cryptogams. 4. The gymetophyte is small or inconspious.
5. The sex organs are multicellular.
6. The fertilization requires water medium results in the formation of zygote. 7. They show distinct alternation of generation.
Example : Selaginella, Adiantum, Dryopteris.
PHANEROGAMAE: - They are seed bearing plants. The plants body is differentiated into ture stem, leaves and root. A well developed vascular system is presents in phanerogames. Sex organs are multicellular.
On the basis of fruit formation, they are classified into two subdivisions. (a) Gymnosperme and (b)Angiosperme
(a). GYMNOSPERME:- the term is made from two Greek words : gymo – means naked and sperme means seed. The plants of this group bear naked seeds and are usually pereneal, evergreen and woody. It has nearly 650 living species. They chief characteristics are:-
1. They have well developed vascular tissues but lack vessels. The ‘flowers’ compose two types of sporophylls i.e., microsporophylls and megas[orohylls.
2. The pollination is anemophilous and the fertilization does not require water medium. There is formation of pollen tube. (Siphonogamous)
3. The zygote develops into an embryo.
4. Since the ovules are not covered by a cattel there is no fruit formation. They are naked.
Example : Cycas, Pinus and Emphedra etc.
(b). ANGIOSPERMAE:- The word is made from two Greek words: anger means covered and sperma means seed. The seeds develop inside an organ which is modified to become a fruit. These are also called flowering plants. They are most abundant and conspicuous plants with about 2,00,000 species. The general characteristics are.
1. They are usually terrestrial plants. The plant body is sporophytic.
2. The plants may be herbaceous or woody. They may be annual, biennial or perennial.
3. A well developed vascular system is present in them. The xylem has vessels.
4. The angiosperms are characterized by the presence of the double fertilization forming a zygote and the primary endosperm, the nutritive tissue.
5. During fertilization the nonflagellate male gametes are carried by a pollen tube (siphon gamous).
6. Fertilized ovules ripens into seed thus the ovary is converted into a fruit. Example : Brassica campestris (Mustard), Pisum santivum (pea) etc. Angiosperms are divided into Monocots and Dicots.
i. Monocot:- monocots bear seeds which have a single cotyledon or seed leaf . the veins on their leave are parallel to each other. Their vascular bundles are arranged in a complex manner.
Example : Palms, Bamboos, Sugar – can, rice etc.
ii. Dicot:- the seeds of dicot have two cotyledons. The veins on their leaves are like a network. Their vascular bundles are arranged in a ring. Their root system consists of a man tap root with smaller branches.
KINGDOM ANIMALAE
Characteristics features of kingdom Animalae are:-
I. The organisms are made up of eukaryotic cells. II. The body of animals is multicellular.
III. The cells do not contain cell wall, but contain only cell membrane.
IV. They do not perform photosynthesis but have heterotrophic nutrition. V. They have the power of locomotion.
VI. They show increased sensitivity through the nervous system.
Basis of animal classification:- They are many features used for distinguishing broad categories of animals. These features include organization, symmetry, body cavity, number of embryonic cell layers and presence of absence of notochord. Organization
Animals are multicellular. But their body cells may or may not be recognized into tissues and organ systems. For example, animals such as sponges are aggregate of cells. They are at a cellular level of organization. Human beings have organs and systems for performing body functions and are at the organ-system level of organization.
Symmetry
Symmetry means dividing the body into equal and identical parts. Sponges are symmetrical. Cnidaria are radially symmetrical and all other animals are bilaterally symmetrical.
Body Cavity
Body cavity or coelom is a cavity between the body wall and the food canal. It is absent in Acoelomates and present in Euoelomates. The body cavity of roundworms is not true and is known as Pseudocoelom.
Embryonic layers
There are three layers of cells-ecotoderm (outer layer), mesoderm (middle layer), and endoderm (inner layer) in the embryo which give rise to parts of the body of animals. Sponges and Cnidaria do not have mesoderm in their embryos and are called diploblastic. Others animals have three layers of cells and are called triploblastic.
Notochord
The notochord is a stiff rod running along the body, close to the dorsal surface. The notochord helps to provide support to the animal. All chordates possess a notochord at some stage of their development. The notochord is absent in vertebrate animals, also termed as non-chordates.
Mammalia (1) PORIFERA:-
The word means organisms with hopes. These are non-motile animals attached to some solid support. They have holes all over the body. These animals are covered with a hard outside layer or skelton. They are commonly called sponges and are mainly found in marine habitats. Example: Euplectelia; sycon etc.
(2) COELENTERATA:-
These are aquatic animals. They show body. The body is made of two layer of cells; one makes up cells on the outside and the other makes the inner living body of the body. They have a gut cavity with a single opening for food and waste material. Example: hydra, Jellyfish.
(3) PLATHELMINTHES:-
These are generally called flatnorms they do not have a body cavity. The body is bilaterally symmetrical. Some of them are free, living in water and soil, but most are parasites. There are three layers of cells in them and thus are called triploblastic. They range from a few millimeters to a few centimeters in size. Reproduction is mostly sexual. Example: Planarians, Liverflukes.
(4) NEMATODA:-
The organisms belonging to this group are mostly parasites having selender, elongated bodies. Tapering at each end. There body is bilaterally symmetrical and triploblastic. These cause diseases such as elephantiasis etc. Example: Ascaris, Lumbricoides.
(5) ANNELIDA:- ‘Annelid’ means ringed. The annelids are worms with body appearing as if made up of series of rings. Annnelids are a coelomates, triploblastic animals. There is extensive organ differentiation. There body is segmented. Each segment posseses a similar pattern of organs. These may be equatic or terristerials and some live in tubes. Example: Earthworms, leaches.
(6) ARTHROPODA:- ‘Artho’ means joined and ‘pod’ means legs. Thus, arthopropoda means jointed legs. These are triploblastic coelomates. They metamerically segmented. These have an open circulatory system. The coelomic cavity is blood-filled. They possess a hard exoskeleton. Sexes are usually separate. Example : Prawns, Butterflies, Hies, Crabs.
(7) Mollusca:- the mollusca are animals with a coelomate triploblastic body. There is bilateral symmetry. They have an open circulatory system and kidney like organs for excretion. The body is often protected by a shell. They a muscular foot to move. Sexes are separate or united. Example: Snails, Mussels.
(8) ECHINODERMATA:- ‘Echinos’ means hedgehog, and ‘derma’ means skin. These are spiny skilled organisms. They are exclusively free-living marine animals. They are triploblastic and have a coelomic cavity. They have peculiar features of regeneration of lost parts. Sexes are separate.
Example: Starfish and sea urching.
(9) PROTOCHORDATA:- these are bilaterally symmetrical, triploblastic coelomate animals. Notochord is present at some stage at some stage of their life history. These are marine animals they have a closed blood system, they have a post-anal tail. Example: Herdemania, Amphioxus.
(10) VERTEBRATA:- these animals have a true vertebral column and internal skelton vertebrates are bilaterally symmetrical, triploblastic, Coelomic and segmented, with complex differentiated of body tissues and organs.
(1). PISCES:- These are fish and live exclusively in water. Their skin is covered with scales. They use oxygen dissolved in water by gills. They are cold – blooded and their health have only two chambers. They lay eggs. The two important classes of fishes are cartilaginous fishes and osteichthyes fishes. Example: sharks, Tuna, Rohu etc. (2). AMPHIBIANS:-Amphibians means ‘Amphi’ ‘double’ and bias ‘life’. They are partly adapted to live on land, and partly in water. Most amphibians lay their eggs in water. These have three chambered hearts. Example: Frogs, Toads and salamanders etc.
(3). REPTILES:- these animals can lively solely on land and are very less dependent on water. These are cold blooded, have scales and breathe through lungs. These have three chambered heart (except crocodiles). They lay eggs covered with waterproof shells. Their skin is water proof and is covered with waterproof horny scales. Example: Lizards, Snakes, Crocodiles, and Dinosaurs.
(4). AVES:- ‘AVIS’ means birds, evolved from reptiles and have many similarities with them. These are warm-blooded and have a four chambered heart. They lay eggs. Birds are distinguished because their bodies are covered with feathers, and two forelimbs modified for flight. They breathe through lungs. Examples: Cuckoo, crow, Sparrow etc.
(5). MAMMALIA:- Mammals are warm-blooded animals with four-chambered hearts. They have mammary glands for the production of milk to nourish their young. Their skin has hairs as well as sweet and oil glands. Most mammals give birth to their young their ones. Sexes are separate. Example: Man, Tiger, At etc.