Classification – The Kingdoms PDF

Name: Date: Classification – The Kingdoms Viruses Viruses are non-cellular organisms, which made up of genetic material and protein that can invade living cells. These micro organisms belong to the family of viridae and Genus of virus. A virus is non-cellular organisms made up of genetic material a...

Name: Date: Classification – The Kingdoms Viruses Viruses are non-cellular organisms, which made up of genetic material and protein that can invade living cells. These micro organisms belong to the family of viridae and Genus of virus. A virus is non-cellular organisms made up of genetic material and protein that can invade living cells. They are considered both a living and non-living thing. The study of viruses is called as Virology. Viruses are very small, and they measured in nanometers. They can only be seen with an electron microscope. They are composed of a core of DNA or RNA surrounded by a protein coat they can only reproduce by infecting living cells. Their size ranges from 20 nanometers to 250 nanometers. Structure of Viruses Characteristics of Viruses Below you could see characteristics of viruses:  They are enclosed in a protective envelope.  They have spikes, which helps them to attach to the host cell.  They are non-cellular.  They do not respire, do not metabolize and do not grow but they do reproduce.  They contain a protein coat called the capsid.  They have a nucleic acid core containing DNA or RNA.  Ribosomes and enzymes are absent, which are needed for metabolism.  They are considered both as living and non-living things, as viruses are inactive when they are present outside of host cells and are active in side of host cells. As they make use of raw materials and enzymes of the host cell to reproduce and causes several infections. 1 Advantages of Viruses They are use full in delivering genes to target cells and play a vital role in and gene therapy researches. Disadvantages of Viruses There are many pathogenic viruses, which causes harm for human beings, plants and animals. In human beings the diseases caused by viruses are: HIV, influenza, herpes, hepatitis small pox, cowpox, etc. The diseases caused by viruses in plants are tobacco mosaic viruses, etc. The diseases caused by bacteria in animals are bovine tuberculosis etc. Different Types of Viruses Diseases can be defined as a disorder, infections or malfunction of the cells, tissues, organs and different parts of our body. If these diseases are left unrecognized or not diagnosed on time, results to the death of an individual. There are many diseases, which varies in modes of transmission, diagnosis, symptoms and treatments. There are two types of diseases. Infectious diseases: These are the diseases, which are caused by pathogenic organisms like: bacteria, viruses, fungi, protozoa, etc. They are spreading disease and can be infected by eating, touching, drinking or by breathing something that contains germs. These diseases can also spread when we meet someone who has been infected. Non-infectious diseases: These are the diseases, which are neither caused by any pathogenic organisms, nor by spreading from an infected person. These diseases are generally caused by genetical disorder, environmental factors or by deficiencies in nutrition. Viruses are non-living strands of genetic material, which are coated with a protein coat. They are non- motile and cannot reproduce by their own, hence they are considered non-living. Different types of viruses and diseases caused by them: Polio, AIDs, HIV, Measles, ETC.  Note: Archaea -plural noun: archaea; noun: archaebacterium; plural noun: archaebacteria - microorganisms which are like bacteria in size and simplicity of structure but radically different in molecular organization. They are now believed to constitute an ancient group which is intermediate between the bacteria and eukaryotes. 2 Kingdom Monera (Bacteria) Kingdom Monera - All the organisms of this kingdom are prokaryotes. Complex structure was the basis of classification of organisms, many centuries ago. According to R.H. Whittaker's five kingdom classification all the bacteria were placed under the Kingdom Monera. Monera are considered as the most primitive group of organisms. They include various types of bacteria and blue-green algae. Monerans are most abundant of all organisms, due to their versatility of their habitat. It is estimated that a single drop of water contains 50 billion bacteria. General characteristics of the kingdom Monera are as follows:  They are primitive organisms.  All organisms of the kingdom are prokaryotes.  They are present in both living and non-living environment.  They can survive in harsh and extreme climatic conditions like in hot springs, acidic soils etc.  They are unicellular organisms.  Membrane bound nucleus is absent.  DNA is in double stranded form, suspended in the cytoplasm of the organism, referred as nucleoid.  A rigid cell wall is present.  Membrane bound cellular organelles like mitochondria are absent.  Habitat - Monerans are found everywhere in hot springs, under ice, in deep ocean floor, in deserts and on or inside the body of plants and animals.  Nutrition - autotrophs - can prepare their own food, heterotrophs - depend on others for food, saprophytes - feed on dead and decaying matter, parasitic - live on other host cells for survival and cause, symbiotic - in mutual relation with other organisms, commensalism - it is where one organism is benefited and the other is not affected, mutualism - where both the organisms are benefited.  Respiration - respiration in these organisms vary, they may be obligate aerobes - the organisms must have organisms for survival; obligate anaerobes - the organisms cannot 3  survive in the presence of oxygen; facultative anaerobes - these organisms can survive with or without oxygen.  Circulation - is through diffusion.  Movement - is with the help of flagella.  Reproduction is mostly asexual, sexual reproduction is also seen. Asexual reproduction is by binary fission, sexual reproduction is by conjugation, transformation and transduction. Kingdom Protista All single celled organisms are placed under the Kingdom Protista. The term Protista was first used by Ernst Haeckel in the year 1886. This kingdom forms a link between other kingdoms of plants, animals and fungi. Protists represent an important step in early evolution. The first protists evolved probably 1.7 billion years ago. Members of Protista are primarily aquatic in nature. It is a very large group comprising of at least 16 phyla. Many protists like algae are the primary producers in the aquatic ecosystem, some protists are responsible for serious human diseases like malaria and sleeping sickness. General characteristics of Kingdom Protista are as follows:  They are simple eukaryotic organisms.  Most of the organisms are unicellular, some are colonial, and some are multicellular like algae.  Most of the protists live in water, some in moist soil or even the body of human and plants.  These organisms are eukaryotic, since they have a membrane bound nucleus and endomembrane systems.  They have mitochondria for cellular respiration and some have chloroplasts for photosynthesis.  Nuclei of protists contain multiple DNA strands; the number of nucleotides is significantly less than complex eukaryotes.  Movement is often by flagella or cilia. 4   Protists are multicellular organisms, they are not a plant, animal or fungus.  Respiration - cellular respiration is primarily aerobic process, but some living in mud below ponds or in digestive tracts of animals are strict facultative anaerobes.  Nutrition - they can be both heterotrophic or autotrophic.  Flagellates are filter feeding, some protists feed by the process of endocytosis (formation of food vacuole by engulfing a bacteria and extending their cell membrane).  Reproduction - some species have complex life cycle involving multiple organisms. Example: Plasmodium. Some reproduce sexually and others asexually.  They can reproduce by mitosis and some are capable of meiosis for sexual reproduction.  They form cysts in adverse conditions.  Some protists are pathogens of both animals and plants. Example: Plasmodium falciparum causes malaria in humans.  Protists are major component of plankton. Kingdom Fungi The organisms in kingdom fungi include mushrooms, yeasts, molds, rusts, smuts, puffballs, truffles, morels, and molds. More than 70,000 species of fungi have been identified. The fungi constitute and independent group to that of plants and animals. They live everywhere in air, in water, on land, in soil, and on or in plants and animals. Some fungi are microscopic and other extend for more than a thousand acres. Mycology is a discipline of biology which deals with the study of fungi. Fungi appear like plants but are closely related to animals. Fungi are not capable of producing their own food, so they get their nourishment from other sources. Fungi are in a wide variety of sizes and forms and have great economic importance. 5 General characteristics of fungi are as follows:  Fungi are eukaryotic organisms.  They are non-vascular organisms.  They reproduce by means of spores.  Depending on the species and conditions both sexual and asexual spores may be produced.  They are typically non-motile.  Fungi exhibit the phenomenon of alteration of generation.  The vegetative body of the fungi may be unicellular or composed of microscopic threads called hyphae.  The structure of cell wall is similar to plants but chemically the fungi cell wall is composed of chitin.  Fungi are heterotrophic organisms.  They fungi digest the food first and then ingest the food, to accomplish this the fungi produce exoenzymes.  Fungi store their food as starch.  Biosynthesis of chitin occurs in fungi.  The nuclei of the fungi are very small.  During mitosis the nuclear envelope is not dissolved.  Nutrition in fungi - they are saprophytes, or parasites or symbionts.  Reproduction in fungi is both by sexual and asexual means. Sexual state is referred to as teleomorph, asexual state is referred to as anamorph. 6 Name: Date: Classification – The Kingdoms Kingdom Plantae There are different types of plant species, which are found on planet earth. They are sorted and classified into a separate kingdom known as Kingdom plantae. This classification is based on their similarities and differences. The Kingdom plantae is also called as kingdom Metaphyta. The Kingdom plantae includes all types of eukaryotic, multicellular, photosynthetic plants found in this biosphere. Most of the organism in this kingdom is autotrophs, which synthesis their own food with the help of solar energy. There are very few species, which are both autotrophs and heterotrophs. The history of life on earth and the success of many organisms literally depend on the success of plants. Below you could see characteristics for kingdom plantae:  Most of the plants are eukaryotic and chlorophyll containing organisms.  Cell walls of plant cells are comprised of cellulose.  They have an ability to grow by cell division.  In life cycle of plant cells, the interchanges occur from the embryos and are supported by other tissues and self produce.  Plants have both organs and organ systems.  They obtain their energy from sun through photosynthesis.  Plants reproduce both by sexual and asexual.  Plants develop a self defence mechanism to protect them from being destroyed by animals, fungi and other plants.  Organisms within Kingdom Plantae are multicellular, eukaryotic and autotrophic.  They lack motility. The Kingdom plantae can be defined as multicellular, autotrophic eukaryotes, which conduct photosynthesis. All member of this family comprises of true nucleus and advanced membrane bound organelles. They are quite different from animals. The Kingdom Plantae contains about 300,000 different species of plants. Among the five kingdoms, Kingdom plantae is a very important, as they are the source of food for all other living creatures present on planet earth, which depends on plants to survive. This kingdom includes all types plants like herbs, shrubs, trees, creepers, climbers, aquatic plants, desert plants, mountain plants, flowering and non-flowering plants, etc. 7 Kingdom Plantae Classification The Kingdom Plantae contains about billion types of plants species and it was very difficult to identify different types of species. Many biologists contributed in classifying different plants species in to their separate kingdom. Based on their classification, plants are divided into the four main groups. These classifications were based on  The presence of vascular tissue.  The absence of vascular tissue.  The presence of seeds.  The absence of seeds. Vascular tissue and the seeds are mainly considered as they play a vital role in: Vascular tissue helps in transporting substances (water, minerals and sugars) throughout the plant. Seeds are structures, which contains an embryo that helps in storing food. Phylum Bryophyta  They are non-vascular land plants, which do not contain any conducting tissues and are often referred to as bryophytes.  These plants are small, grow close to the ground and include mosses and liverworts.  They are very small in structure and are considered as important members of our ecosystem.  The reproduction process is carried in their spores. They are non- flowering plant and are found mainly growing on the ground, on other plants and on rocks.  They play a vital role in preventing soil erosion. Phylum Bryophyta e.g.: Mosses, Liverworts and Hornworts. Mosses Phylum Pteridophyte  They are seedless vascular plants, which contain vascular tissues but do not produce seeds.  They are involved in transportation of fluids.  The reproduction process is carried by spores. Phylum pteridophyte e.g.: horsetails, ferns and club mosses. Horsetails Phylum Angiosperms 8   Angiosperms are flowering plants, which develops the seeds within a protective structure.  The reproduction process is carried by Angiosperm.  They develop their seeds within an ovary, which itself is embedded in a flower. After the stage of fertilization, the flower falls and the ovary bulges to become a fruit.  Angiosperms in the class Dicotyledoneae grows into two seed-leaves (cotyledons).  An angiosperms leaf consists of a single, branched, main vein, which originates from the base of the leaf blade. In few plats, it may also consist of four or more main veins diverging from the same base. Phylum angiosperms e.g.: trees, shrubs, vines and flowers. Vines The angiosperms, or flowering plants, are the most dominant and ubiquitous vascular plants of present-day flora. These plants are primarily responsible for changing the green and yellow melancholy of the earth’s vegetation. They do so by their beautiful and colourful brightness and fragrance of their flower. The term angiosperm means ‘enclosed seed’. This is so because the ovules or potential seeds are enclosed within a hollow ovary. We can divide the plants of Angiosperms into two major groups as – Dicotyledons and Monocotyledons. Dicotyledons They show the following distinguishing characteristics:  We see taproots in the members of this group.  The leaves in members of these class exhibit reticulate (net-like) venation.  The flowers are tetramerous or pentamerous having four or five members in the various floral whorls, respectively.  The vascular bundles arranged in a ring, number 2–6, open and with cambium.  The seeds of dicotyledons are with two cotyledons as the name indicate. Monocotyledons They show following distinguishing characteristics:  We see adventitious roots in the members of this group.  The leaves are simple with parallel venation.  The flowers are trimerous. They have three members in each floral whorl.  The vascular bundles scattered in the ground tissue, many in number, closed and without cambium.  The seeds of monocotyledons are with one cotyledon as the name indicates. e.g., Cereals, bamboos, sugarcane, palms, banana, lilies and orchids. 9 Phylum Gymnosperms  Gymnosperms are non-flowering plants with undeveloped seeds, which are present in an enclosed structure.  Monocot begins with a single seed-leaf. The main veins of their leaves are usually parallel and unbranched.  Monocot plays an important role in providing us with our primary sources of nutrition, which includes grains, fruits, etc. Phylum gymnosperms e.g.: palms, carpet lawns, etc. Palms Kingdom Animalia 10 The major group of animals are classified under the Kingdom Animalia, also known as Metazoa. This kingdom does not contain prokaryotes. All the members of this kingdom are multicellular, eukaryotes. They are heterotrophs, they depend on other organisms directly or indirectly for food. Most of the animals ingest food and digest in the internal cavity. Most of the organisms are motile which means they can move independently and spontaneously. There are around 9 to 10 million species of animals, and about 800,000 species are identified. Fossil records of animals were found in the era of the Cambrian explosion, about 540 million years ago. Animals are divided into various sub-groups, biologists have identified about 36 phyla within the animal kingdom including birds, mammals, reptiles, fish, amphibians etc. General characteristics of the Kingdom Animalia are as follows:  Animals are eukaryotic, multicellular and heterotrophic organisms.  They have multiple cells with mitochondria and they depend on other organisms for food.  Habitat - Most of the animals inhabit seas, fewer are seen in fresh water and even fewer on land.  There are around 9 to 10 million animal species that inhabit the earth. Only 800,000 species are identified.  Biologists recognize 36 phyla in the animal kingdom.  Size - The sizes of animals ranges from a few celled organisms like the mesozoans to animals weighing many tons like the blue whale.  Animal bodies - Bodies of animals are made of cells organized into tissues which perform specific functions in most animal tissue is organized into complex organs, which form organ systems.  Cell structure - The animal cell contains organelles like the nucleus, mitochondria, Golgi complex, ribosomes, endoplasmic reticulum, lysosomes, vacuoles, centrioles, cytoskeleton.  Animals are made up of many organ systems, that aids in performing specific functions that are necessary for the survival of the organism.  Organ systems are skeletal system, muscular system, digestive system, respiratory system, circulatory system, excretory system, reproductive system, immune system and the endocrine system.  Body symmetry - Most of the animals are bilaterally symmetrical, while primitive animals are asymmetrical, and cnidarians and echinoderms are radially symmetrical.  Locomotion - Most animals have the ability to move, they show rapid movement when compared to plants and other organisms.  Respiration - It is a gaseous exchange of taking in oxygen and giving out carbon dioxide. This process takes place in organs of respiration like the lungs, gills, book gills and book lungs and some animal skin are also used for respiration.  Digestion - Animals ingest food, and digestion takes place in the internal cavity like the digestive system in animals, in primitive animals’ vacuoles are for digestion. 11   Nervous system - Sensory mechanism and the coordination of the organ systems is carried on by the nervous system. In animals the nervous system comprises of nerve ganglions, or brain, spinal cords and nerves.  Circulatory system - The distribution of nutrients, exchange of gases and removal of wastes takes place in the circulatory system. This system comprises of the heart, blood vessels and the blood.  Excretory system - Removal of wastes from kidneys.  Skeletal system - support and protection is provided by the skeletal system.  Reproductive system - Most animals reproduce sexually, by the fusion of haploid cells like the eggs and the sperms.  Glands of the endocrine system help in control and coordination of the body system. Kingdom Animalia Classification Kingdom Animalia has approximately 36 sub-divisions known as 'phyla'. Each phyla share particular properties structurally and functionally which together separate it from other phyla. Below are the most common phyla classified under traditional biological methodology. Phylum Porifera - They are primitive organisms, most of them are salt-water sponges. They do not have organs or nerve cells or muscle cells. Approximately, 8,000 species exist today. Example: Sycon, Euspongia, Spongilla. Phylum Coelenterate (Cnidaria) - This group is composed of jelly-fish and other lower aquatic animals. Approximately, 15,000 species exist today. Example: Aurelia, Adamsia. Phylum Platyhelminthes - This group consists of flat worms. They inhabit both marine and fresh water habitats and they are mostly endoparasites found in animals. Example: Taenia, Fascicola. Phylum Aschelmeinthes - It is a group of round worms, most of them are parasites. This phylum consists of about 80,000 parasitic worms. Phylum Annelida - They are present in aquatic, terrestrial and are free-living or parasitic in nature. This phylum comprises of segmented worms. Example: Earthworm, Leech etc. Phylum Arthropoda - This is the largest phylum which consists of insects. There are over 1 million species of insects existing today. Example: Locusts, Butterfly, Scorpion, Prawn. Phylum Mollusca - It is the second largest phylum. They are terrestrial and aquatic. Example: Pila, Octopus. Phylum Echinodermata - This consists of sea stars and sea urchins. There are about 6,000 species. Example: Asteria, Ophiura. Phylum Chordata - Animals of this phylum have a characteristic feature of presence of notochord, a dorsal hollow nerve cord and paired pharyngeal gill slits. Within this phylum advanced group called vertebrates which include fish, amphibians, reptiles, birds and mammals. 12 Invertebrates Invertebrates are the most abundant organisms on earth. They occupy almost all habitats, they can be found crawling, flying, swimming or floating. Invertebrates are the animals without backbone. These animals do not have internal skeleton made of bone. They play a vital role in the earth's ecosystem. About 99 per cent of the known organisms are invertebrates. Out of the planets estimated 15-30 million species about 90% of the animals are invertebrates. These come in may shapes and sizes and provide services that are vital for our survival. The most common vertebrates include sponges, annelids, echinoderms, molluscs and arthropods. Arthropods includes insects, crustaceans and arachnids. The earliest fossil of an invertebrate dates back towards the late Precambrian period, over 600 million years back. What are Invertebrates? Invertebrates are the animals that do not have a backbone or the vertebral column. Animals without the notochord are invertebrates. Most of the animals are invertebrates. The term invertebrate is a prefixed form of a Latin derived word 'Vertebra'. 'Vertebra' means joint in general, specifically it means 'the joint of the spinal column of the vertebrate'. It is coupled with the prefix "in" meaning not or without, which conveys the meaning 'those that lack vertebrae'. Invertebrates are the most diverse group having about 12 million live species. Most of the animals on earth are invertebrates. They are cold-blooded animals; their body temperature depends on the temperature of the atmosphere. Characteristics of Invertebrates General characteristics of invertebrates are as follows:  The main characteristic that separates invertebrates from other organisms is the absence of the spinal column and backbone.  They are multicellular organisms, they completely lack cell walls.  They are devoid hard bony endoskeleton.  Due to the lack of complex skeletal systems, some invertebrates tend to be slow and small in nature.  Due to the lack of the backbone and complex nervous system the invertebrates cannot occupy multiple environments, though they are found in the harshest of the environments.  Invertebrates live all over the world in various habitats.  Body is divided into three parts - head, thorax and the abdomen.  They do not have lungs for respiration.  Respiration is through skin. 13   Some invertebrate groups possess a hard, chitinous exoskeleton.  Most of them have tissues, that are specific organization of cells.  Most of them reproduce sexually by the fusion of the male and female gametes.  Few invertebrates like the sponges are sedentary, but most of the organisms are motile.  Most invertebrates are organized with symmetric body organization.  They can not make their own food, are heterotrophs. List of Invertebrates Invertebrates are the most diverse organisms present on earth. Almost 95% of the animal populations are of the invertebrates. Based on the International Union regarding Conservation of Nature at the time of 2009 more than 1.3 million invertebrates were identified. Invertebrates make up around 75% of the recognized species on Planet. The actual number of invertebrates is unknown, there are several predictions that there may be tens of millions of invertebrates, majority being the insects. New species of invertebrates are being discovered regularly, another worrying fact is that there is insufficient information about these organisms, the invertebrates might be going extinct and the scientists would never know that they even existed. Below are a list of invertebrates - Crustaceans, Centipedes, Ants, Wasps, Spiders, Locusts, Honey bees, Termites, Cockroach, Grasshoppers, Crickets, Stick insect, Mantis, Crabs, Sponges, Star fish, Unio, Leeches, Earthworms, etc. Invertebrates Classification Some invertebrate phyla are: Phylum Porifera (Sponges)  Members of this phylum are commonly known as sponges.  Habitat - They are mostly marine, few are found in fresh water.  Body symmetry - mostly are asymmetrical animals, no definite shape to the body.  Level of organization - These are primitive animals, multicellular with cellular grade of organization.  Motility - Adult sponges are sessile, that is they need a substratum to attach themselves to a surface and do not move.  Mode of Nutrition - Due to the sessile nature, sponges are filter feeders.  Digestion - Digestion is intracellular.  Skeleton - The body of sponges is supported by a skeleton made of spicules or spongin fibres. 14   Reproduction - Sexes are not separate, they are hermaphrodites. Hermaphroditism - condition where eggs and sperms are produced by the same individual. Sponges reproduces asexually by fragmentation and sexually by formation of gametes.  Fertilization - Fertilization is internal.  Development - Indirect development, having a larval stage which is morphologically distinct from the adult.  Water transport or Canal system - Sponges have water transport system. Water enters through minute pores (ostia) in the body wall into a central cavity known as spongocoel. From the spongocoel water goes out through the osculum. This water system aids in food gathering, respiratory exchange and removal of wastes.  Choanocytes - These are collar cells, they line the spongocoel and the canals.  Examples: Sponges, Sycon (scypha), Spongilla (fresh water sponge) and Euspongia (bath sponge). Phylum Cnidaria (Coelenterate)  Habitat - They are aquatic mostly marine animals, they are sessile or free-swimming.  Level of organization - They exhibit tissue level of organization.  Body wall - They are diploblastic animals, body wall is made of 2 layers, outer ectoderm and inner endoderm.  Body symmetry - They are radially symmetrical.  Digestive system - They have a central gastro-vascular cavity with a single opening hypostome, which serves as both the mouth and the anus.  Digestion is extracellular and intracellular.  Specialized cells known as the cnidoblasts or cnidocytes which contain the stinging capsules or nematocytes are present on the tentacles and the body. Cnidoblasts are used for anchorage, defence and for the capture of prey.  Some cnidarians like corals have skeleton composed of calcium carbonate.  Cnidarians exhibit two basic body forms called polyp and medusa. The polyp is a sessile form a cylindrical in shape like the Hydra, Adamsia etc. The medusae form is umbrella shaped and free-swimming forms like Aurelia or jelly-fish.  Metagenesis - Cnidarians which exhibit both polyp and medusae form are exhibit alteration of generation, this is known as metagenesis. Poplyps produce medusae asexually and medusae form the polyps sexually.  Locomotion - The body contains nerve network that allows movement of tentacles and body.  Examples: Aurelia (medusa), Adamsia (polyp), Hydra, Sea anemones, Physalia (Portugese man-of-war), Pennatula (sea-pen), Gorgonia (sea-fan), Meandrina (brain coral). 15 Phylum Ctenophora:  Ctenophores are commonly known as sea walnuts or comb jellies.  Habitat - They are exclusively marine animals.  Body symmetry - They are radially symmetrical.  Body wall - They are diploblastic organisms.  Level of organization - Ctenophores exhibit tissue level of organization.  Digestion is both extracellular and intercellular.  Locomotion - The body bears eight external rows of ciliated comb plates, these help in locomotion.  Bioluminescence is a property of living organism to emit light is well-marked in ctenophores.  Reproduction - Sexes are not separate, reproduction is by sexual means only.  Fertilization is external with indirect development.  Example: Pleurobrachia and Ctenophora. Phylum Platyhelminthes  They are commonly called as flatworms, they have dorso- ventrally flattened body.  Habit - They are mostly endoparasites found in animals and human beings.  Habitat - Fresh-water and salt water; terrestrial.  Body symmetry - Flatworms are bilaterally symmetrical.  Body wall - They are triploblastic animals.  Coelomic cavity - They are acoelomate animals  Level of organization - Organ level of organization.  Digestive system - In flatworms’ digestive system is incomplete, that is the digestive cavity has a single opening.  Parasitic flatworms possess hooks and suckers to hold on to the body of the host. Some forms absorb nutrition directly from the host, through their body surface.  Osmoregulation and excretion are carried out by specialized cells flame cells.  Sexes are not separate.  Fertilization is internal, and development is indirect, having many larval stages.  Some members like Planaria possess high regeneration capacity.  Examples: Taenia (tapeworm), Fasciola (liver fluke). 16 Phylum Aschelminthes (Nematoda)  The body of worms of aschelminthes in cross-section is circular, hence the name round worms.  Habitat - They may be free-living, aquatic and terrestrial or parasitic in plants and animals.  Level of organization - Round worms have organ-system level of organization.  Body symmetry - They are bilaterally symmetrical.  Body wall - They are triploblastic animals.  Coelomic cavity - They are pseudocoelomate animals.  Digestive system - This is the first phylum to have a complete digestive system, with a well- developed muscular pharynx.  Excretory system - An excretory tube removes body wastes from the body cavity through the excretory pore.  They are dioecious - the sexes are separate i.e.; males and females are distinct. Often females are longer than the males.  Fertilization is internal.  Development may be direct - the young ones resemble the adult, or indirect.  Examples: Ascaris (round worm), Wuchereria (filaria worm), Ancylostoma (hookworm). Phylum Annelida (Segmented worms)  Habitat - They may be aquatic either marine or fresh water; or terrestrial; free-living and sometimes parasitic.  Level of organization - They exhibit organ-system level of body organization and bilateral symmetry.  Body wall - They are triploblastic.  Coelom - They are coelomate animals.  Body is metamerically segmented. The body surface is distinctly marked out into segments of metameres and hence, the phylum name Annelida.  Locomotion - They possess longitudinal and circular muscles which help in locomotion.  Aquatic annelids posses lateral appendages, parapodia which help in swimming.  Circulatory system is closed.  Osmoregulation and excretion are by Nephridia.  Neural system - It consists of paired ganglia connected by lateral nerves to a double ventral nerve cord.  Nereis is dioecious, but earthworm and leeches are monoecious. 17   Reproduction is sexual.  Examples: Nereis, Pheretima (earthworm), and Hirudinaria (blood sucking leech) Phylum Arthropoda  It is the largest phylum of the Animalia.  It includes insects, spiders, crayfish, etc.  Level of organization - They have organ-system level of organization.  Body symmetry - They are bilaterally symmetrical.  Body wall - triploblastic, segmented. Coelomate animals.  The body of arthropods is covered by chitinous exoskeleton.  Body is divided into head, thorax and abdomen.  Jointed appendages - arthros - jointes, poda - appendages, hence the name is derived from this characteristic.  All the arthropods have jointed appendages which give arthropods a wide range of controlled motions.  Respiration is through organs like gills, book gills, book lungs or tracheal system.  Circulatory system - It is of open type. Sensory organs are present, antennae, eyes (compound and simple), statocysts or balance organs are present.  Excretion - It takes place through malphigian tubules.  Mostly they are dioceious. Fertilization is usually internal.  They are oviparous animals.  Development may be direct or indirect.  Examples: Apis (honey bee), Bombyx (silkworm), Laccifer (lac insect); Mosquitoes - Anopheles, Culex and Aedes; Locusta (locust); Limulus (king crab). Phylum Mollusca  It is the second largest phylum.  Habitat - Molluscs are terrestrial or aquatic; they may be marine or fresh water.  Level of organization - They have an organ-system level of organization.  Body symmetry - Bilaterally symmetrical.  Body wall - triploblastic. Coelomate animals.  Body is covered by a calcareous shell. 18   Body is unsegmented, they have a distinct head, muscular foot and visceral hump.  The radula - Mouth of the molluscs contain tongue-like organ called radula, which has many rows of teeth, which is used to scrape food.  Mantle - It is a fold of skin that surrounds the body organs.  It is a soft and spongy layer of skin that forms a mantle over the visceral hump.  The space between the hump and the mantle is called the mantle cavity.  Feather like gills are present in this cavity.  These gills have respiratory and excretory in functions. Anterior head region has sensory tentacles.  Example: Chaetopleura (Chiton), Loligo (squid), Pila (apple snail), Pinctada (pearl oyster), Sepia (cuttlefish), Loligo (squid), Octopus (devil fish), Aplysia (sea hare), Dentalium (tusk shell). Phylum Echinodermata  All the members are marine, live mainly on the ocean floor.  These animals have an endoskeleton of calcareous ossicles, and hence the name echinodermata (spiny bodied).  Level of organization - Organ-system level of organization.  Body symmetry - The adults are radially symmetrical, but the larvae are bilaterally symmetrical.  Body wall - Triploblastic. Coelomate animals.  Digestive system is complete.  The mouth is present on the ventral side and anus on the dorsal side.  The most distinctive feature is the water vascular system.  This helps in locomotion, capture and transport of food and respiration.  Excretory system is absent.  Sexes are separate.  Reproduction is by sexual means.  Fertilization is usually external.  Development is indirect with free-swimming larva.  Example: Asterias (star fish), Echinus (sea urchin), Antedon (Sea lily), Cucumaria (sea cucumber), Ophiura (brittle star). Invertebrates include all animals that do not belong the phylum Chordata. Common examples include clams, snails, spiders, cockroach, worms, star fish, octopus. 19 Vertebrates Vertebrates are the most organized organisms on Earth. They belong to the sub-phylum Vertebrata. They are not the most numerous groups of animals, they are the most advanced group of animals. The characteristics that makes vertebrates special are the presence of the spinal cords, vertebrae and notochords. Most vertebrates have a very well-developed nervous system. The vertebrates also have muscles and skeletons which help them move around efficiently and perform complex moves. Vertebrates include the majority of the Phylum Chordata, having about 64,000 species described. Vertebrates make about 4% of all described species. Vertebrates have a long history on earth - more than 500 million years, from the Cambrian era until date. First Vertebrates have said to be appeared around the Cambrian period of the Paleozoic era about 525 million years ago, they are said to be adapted to feeding algae in shallow waters and moving around from place to place. Vertebrate are the animals belonging to the sub-phylum Vertebrata. They belong to the Phylum Chordata. The characteristics of phylum chordata is the presence of notochord, a dorsal hollow nerve cord and paired pharyngeal gill slits. The members of subphylum Vertebrata possess notochord during the embryonic period. The notochord is replaced by a cartilaginous or bony vertebral column in the adult. All vertebrate are chordates, but all chordates are not vertebrates. Special characteristics of vertebrates other than the vertebral column are, they have a muscular heart which is two, three or four chambered. For excretion they have kidneys and appendages that are paired which may be fins or limbs. Vertebrate Characteristics General characteristics of the sub-phylum Vertebrata are as follows:  Vertebrates have a well-developed brain.  Brain is set inside a bony box, known as cranium.  Notochord is present in all chordates during sometime of development, it is formed on the dorsal side of the primitive gut in the early embryo stage.  Most vertebrates possess guts with a non-terminal anus.  The mouth cavity and the oesophagus are connected by the pharyngeal gill slits to a muscular tube pharynx, which opens to the exterior.  They possess a dorsal hollow nerve tube at some stage of their life.  Possess a dorsal cartilaginous nerve rod known as the notochord.  At some stage of their life possess gill slits in the pharyngeal region.  Have partially open circulatory system.  Possess two pairs of appendages.  The endoskeleton is made of cartilage or bone.  The first vertebrates were jawless fishes with single caudal fin. 20   The advancement of vertebrates with a hinged jaw which opened new food options and jawed fishes became the dominant creatures in the sea.  All vertebrates have a heart and closed circulatory system.  Reproduction is normally sexual.  Feed on variety of organic materials.  Unisexual animals have one pair of gonads. Vertebrate Classification Classes of Vertebrates Class – Pisces (Fish) This contains all classes of fish.  Class Chondrichthyes (cartilaginous fish, e.g. sharks) These organisms are marine and have streamlined body. The endoskeleton is cartilaginous. Mouth is located ventrally, and the notochord is present throughout life. The gills are separate and are not covered by the operculum. The skin contains minute placoid scales. The placoid scales are modified as teeth and the jaws are powerful. They are predaceous animals. Air bladder is absent in these animals; hence, they have to swim constantly to avoid shrinking. Example: Scolidon, Pristis, Trygon. 21  Class Osteichthyes (bony fish) This class includes animals that are both marine and fresh water fishes with bony endoskeleton. Their body is streamlined. Mouth is terminal in position. The gills are covered with operculum on each side and are in four pairs. The skin is covered by ctenoid/cycloid scales. Air bladder is present, it regulates buoyancy. Two-chambered heart is present, with one auricle and one ventricle. They are poikilothermic animals. The sexes are separate, fertilization takes place externally. Most of them are oviparous animals and development is direct, with no larval stages. Example: Hippocampus, Clarias. Pisces Example: Sharks, trout, eels, tunas, seahorse, piranhas, salmons, etc. Class – Amphibia (Amphibian) The name Amphibia indicates - from Greek, Amphi meaning dual and bios meaning life. Amphibians can live both in aquatic and terrestrial habitats. These animals have two pairs of limbs. Body is divisible into head and trunk and tail is present in some animals. The skin of these animals is scaleless and moist. The eyes have eyelids, and the ears are represented by a tympanum. Cloaca is an opening to the exterior, it is a common chamber for the alimentary canal, urinary and reproductive tracts. Gills, lungs and skin aids in respiration. Heart is three-chambered. They are cold- blooded animals. Sexes are separate, fertilization is external. They are oviparous animals and development is indirect. Example: Salamanders, frogs, toad, newts, caecilians, etc. Class – Reptilia (Reptile) In Latin repere or reptum means to creep or crawl, hence, the class name refers to locomotion that is of creeping or crawling mode. These animals are mostly terrestrial and their body is covered dry and cornified skin, epidermal scales or scutes. External ear opening is absent, tympanum represents the ear. Limbs, if present are of two pairs. Usually heart is three- chambered but is four chambered in crocodiles. They are poikilothermic animals. Some animals like the snake and the lizards shed their skin. Sexes are separate, internal fertilization takes place. They are oviparous and development is direct. Example: Chameleon, snakes, lizards, tortoise, turtles, crocodiles, gharials, alligators, etc. Class – Aves (Bird) Most of the members can fly, except the flightless birds. The characteristic feature of birds is the presence of feathers. The forelimbs are modified as wings. The hind limbs are modified for walking, swimming or clasping and generally have scales. The skin is dry and does not have glands, except an oil gland at the base of the tail. Endoskeleton is bony, and the bones are hollow with air cavities known as pneumatic bones. Heart is four-chambered 22 completely. They are warm-blooded animals. Lungs are the organs of respiration. Sexes are separate, fertilization is internal. They are oviparous animals and development is direct. Example: Penguins, emu, eagles, ostrich, parrot, crow, pigeon, ducks, owls, kites, robins, woodpeckers, albatross etc. Class – Mammalia (Mammals) Mammals are present in almost all habitats - polar ice caps, deserts, mountains, forests, and grasslands. The unique characteristic of the class mammalia is the presence of milk producing glands (mammary glands), by which the young ones are nourished. The limbs are of two pairs. The skin is covered with hairs. External ear 'pinna' is present. Heart is four-chambered and they are homeothermic animals. Respiration is through lungs. Sexes are separate and fertilization is internal. They viviparous animals, with direct development. Example: Kangaroo, echidna, platypus, bats, mice, tigers, moles, dolphins, whales, deer, gorillas, lemurs, rabbits, wolves, lions, leopards, jackals, etc. List of Vertebrates The vertebrates are a very diverse group of animals ranging from Hag-fish to Man. They are not the most numerous group of animals. Vertebrates are interesting because we are intimately familiar with them, or species Homo sapiens is included within the sub-phylum vertebrata. Vertebrates are easy to find as we co-exist with them and often aware of their presence in our environment. Below is the list of few very familiar vertebrates: deer, fish, dogs, cats, birds, snakes, lizards, kangaroo, bears, foxes, wolves, bat, monkeys, eagles, penguins etc. Comparison of the vertebrate classes 23