CHAPTER TWO CLASSIFICATION OF LIVING THINGS Somali National University
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CLASSIFICATION
Do you know what the word "classification" means?
Classification meaning is a scientific grouping of plants and animals based on their similarities. The “SCIENCE� of classification is called taxonomy. Taxonomy is the field of biology that study how living things are classified.
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Who first developed a system to classify organisms? As early as (384-322 BC) the Greek Philosopher Aristotle created guidelines for grouping living things. Aristotle grouped organisms based on four characteristics: •Body parts •Life histories •Activities •Character Somali National University
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• Aristotle developed the first classification system, which divided all known organisms into two groups: • PLANTS and ANIMALS • Aristotle then divided each of these main groups into three smaller groups. • Animal Subgroups: Land, Water, Air Plant Subgroups: Small, Medium, Large • Aristotle’s classification system was not very good.
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• There were too many organisms that didn’t fit. For example, frogs are born in water and have gills like fish, but when they grow up they have lungs and can live on land. In Aristotle’s classification system, birds, bats, and flying insects were grouped together even though they have little in common except they can fly. But the penguin is a bird that cannot fly. So Aristotle would not have classified them as birds. Somali National University
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John Ray’s classification • John Ray is considered the first scientist who tried to classify living organisms according to similarities in their external features (Morphological), but John Ray’s classification did not offer a better classification than Aristotle. Somali National University
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The Modern Classification System The modern classification system was developed by the Swedish scientist, Carolus Linnaeus ( father of taxonomy ), in the mid 1700’s. His system was based upon classifying organisms according to the organism’s physical and structural similarities. Some characteristics he used to classify organisms were outside appearance, internal organs, and how body systems worked. Modern scientists are still using most of Linnaeus’s classification 7 Somali National University system.
• Carolus Linnaeus used a scientific principle which still applied till now called Natural Taxonomy. The purpose of this classification is to facilitate its identification and study. Linnaeus followed three main principles in his classification. 1- Using Latin language (because of being an old language and not spoken by people so, it has been protected from any change or modification). 2- Using binomial system of nomenclature ( each living organisms has a name consists of two parts, first part represents Genus and it starts with a capital letter, the second part represent species and it starts with a small letter). 3- Series of Taxonomy. Somali National University
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Linneaus’ System of Scientific Names Binomial Nomenclature is a two word classification naming system developed by Linneaus.
Each species of a living thing is given a DOUBLE NAME EX:
Just like your first and second name
First Name (Genus) Tells which group of similar species the living thing belongs to. Genus is ALWAYS capitalized. Second Name (Species) Tells the name of the one particular species in that genus. Species is NEVER capitalized. Somali National University
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How Are Living Things Classified? Kingdom: The highest level Phylum: A subdivision of a kingdom Class: Each phylum is divided into classes Order: Each class is divided into orders Family: Each order is divided into families Genus: Each family is divided into genera Species: Lowest level (represents a single type of organism) Somali National University
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How Are Living Things Classified? Broadest Level
•There are 7 levels in the classification system of organisms •As one goes from the Kingdom to the Species (DOWNWARD)…An increase in the similarity between organisms occur •There are fewer numbers of different kinds of organisms
Most Specific Somali National University
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• Scientists added to the previous classification other sub-classification to e.g classes is divided to sub-classes, phylum is divided into sub-phyla, kingdom is divided into sub-kingdom. • The scientist R.Whittaker suggested the classification of living organisms according to a- Cellular characteristic (cellular structure, presence of plastids) b- Characteristic of nucleus e.g presence of nucleus membrane c- Hereditary studies d- Resemblance of reproductive organs. e- Microscopic examination Somali National University
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The 5 KINGDOMS of Classification A Kingdom is the largest group in the Classification system. It encompasses all the related species.
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The 5 KINGDOMS of Classification In all, there are five Kingdoms of Life‌
1.Monera 2.Protista 3.Fungi 4.Plantae 5.Animalia Somali National University
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1- The Kingdom Monera – is derived from the greek
word Moneres, meaning single. These are the bacteria and the blue-green algae. They consist of single cells but differ from other singlecelled organisms because their chromosomes are not organized into a nucleus. They often lack a nucleus and a cell membrane. There are some harmful bacteria that can cause illness and disease and there are others that are essential for us to survive. Bacteria help to break down dead matter and also food in our digestive system. Most organisms in the monera kingdom are able to reproduce through a process called fissio. Some monera have the ability to move using their flagella but others cannot move on their own. Blue-green bacteria or blue-green algae are a special type of monera kingdom that can produce its own food through photosynthesis. This is because the blue-green algae contain chlorophyll.
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This picture is of E. coli
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• Kingdom Monera has been classified into two groups - Archaebacteria and Eubacteria. • Archaebacteria are microbes that live in harsh conditions, These bacteria lack cell wall, their cell membrane is made up of different lipids, and their ribosomes are similar to that of eukaryotes. Archaebacteria are of three major groups of bacteria based on their habitat i.e., thermophiles, halophiles and methanogens.
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Eubacteria are true bacteria. The characteristic feature is the presence of rigid cell wall and if present a motile flagellum that aids in locomotion. These organisms are characterized based on their nutrition and their shapes. • Classification based on Shape Bacteria can be classified in four groups based on shape : Spherical or round shaped bacteria are called cocci, Rod-shaped are bacilli, Comma-shaped bacteria are vibrio and spiral shaped bacteria are spirilla. • Classification Based on Mode of Nutrition • Based on the mode of nutrition bacteria are broadly classified into Autotrophic and Heterotrophic. • Autotrophic bacteria can be Chemosynthetic or Photosynthetic. • Autotrophic bacteria - Bacteria which prepare their own food are autotrophic. (Example Cyanobacteria) • Photosynthetic bacteria are autotrophic bacteria which prepare their own food by the process of photosynthesis. • Chemosynthetic bacteria are those which prepare their food with the help of inorganic substrates. • Heterotrophic bacteria - Bacteria which are dependent on other organisms for their food are heterotrophic.(Example Escherichia coli) •
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Cyanobacteria (Blue-green algae) - also known as Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis.The name "cyanobacteria" comes from the color of the bacteria (Greek: (kyanós) = blue). They are often called blue-green algae . They have chlorophyll similar to plants and they are photosynthetic autotrophs. The marine and terrestrial and they may be unicellular, colonial or filamentous. The colonies are surrounded by gelatinous sheath. They can also fix atmospheric nitrogen. Example: Nostoc and Anaebena. Chemosynthetic autotrophs - these organisms oxidise substances like nitrites, nitrates, ammonia etc. The help in recycling substances like nitrogen, sulphur, iron etc.
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Heterotrophic bacteria are those which are dependent on other organism either directly or indirectly for their nutrition. They are most abundant and are important decomposers. Some are helpful in curdling milk, production of antibiotics, in nitrogen fixation and some are pathogens. Heterotrophic bacteria can be parasitic and saprophytic. Parasitic bacteria are those which depend on the host for nutrition and cause harm to the host. Saprophytic bacteria feed on dead and decaying matter. Symbiotic - it is a type where the bacteria are in mutual relation with other organisms. Symbiosis is of two types mutualism and commensalism. Mutualism is where the bacteria and the other organismare benefited due to the relationship. Commensalism is a relationship where the bacteria is benefited while the other organism is not affected by the relationship. Somali National University
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• Classification based on Gram's staining • classifying bacteria into Gram positive bacteria and Gram negative bacteria. • Gram Positive Bacteria - The bacteria's cell wall is made up of protein-sugar complex that takes on purple color during gram staining. Gram Negative Bacteria - The gram negative bacteria has an extra layer of lipid on the outside of the cell wall and appear pink during the Gram staining procedure.
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• The Monerans comprises of mostly bacteria. Following are a few well known examples. Blue-green algae - Cyanobacteria, Cocci shaped bacteria - Streptococcus, Bacilli shaped bacteria E.coli, Vibrio shaped - Vibrio cholerae (cholera), Spiral shaped bacteria - Treponema pallidum(syphilis). Gram positive bacteria - Mycobacterium; Gram negative bacteria - E.coli (coliforms)
Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Streptococcus pyogens, Clostridium botulinum, Listeria monocytogenes, Salmonella enterica, Vibrio cholerae, Bacillus anthracis, Bacillus cereus.
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2- Kingdom Protista (Protoctista) These are mostly single-celled (unicellular) organisms which have their chromosomes enclosed in a nuclear membrane to form a nucleus. All are Eukaryotic (have a nucleus) Some of them e.g. Euglena posses chloroplasts and make their food by photosynthesis. These protista are often referred to as Unicellular plants or Protophyta. Organisms such as Amoeba and paramecium take in and digest solid food and thus resemble animals in their feeding. They may be called unicellular animals or protozoa. Example of protista kingdom are Amoeba , paramecium , Euglena and chlamydomonas. Somali National University
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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 are significantly less than complex eukaryotes. • Movement is often by flagella or cilia. • 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. • Some protists are pathogens of both animals and plants. Example: Plasmodium falciparum causes malaria in humans. • Protists are major component of plankton. Somali National University
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Kingdom Protista are classified into two Phyla: Protozoans - animal-like single-celled organisms. Algae - plant-like single or multi-celled organisms.
Animal-like Protists – PROTOZOANS Protists that have resemblance to animals are known as protozoans. They live in moist and watery environments. The characteristics similar to animals are - their ability to move and their inability to produce their own food (heterotrophs). They differ from animals being unicellular while animals are multicellular. • Protozoans are classified on the way they move into four categories: • Sarcordinians - move using pseudopod. • Zooflagellates - move using flagella. • Ciliaphorans - move using cilia. • Sporozoans - forms spores. Do not move. • Phylum Sarcodina - The movement in sarcodinians is by extending lobes of cytoplasm known as pseudopodia. The pseudopoda is used for movement and feeding. Example: Amoeba
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• Phylum Mastigophora (Zooflagellata) - These protozoans move with the help of flagella. Most of them are parasitic. Many flagellates are seen in the intestine of humans, in termites and other animals, some flagellates are harmful. Example: Trypanosoma gambiense causes sleeping sickness in cattle and human. • Phylum Ciliophora (Ciliates) - Protozoans of this phylum move with hair like structures called cilia. The cilia stick out of their cells. The cilia is also used to sweep food particles into the organism. Example: Paramecium - It is a ciliate protozoan found in fresh water and ponds.
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• Plant-like Protists – ALGAE • Plant-like protists have chlorophyll like that in plants. The green substance in their cells enable them to make food by photosynthesis. They produce and release oxygen like the plants. • Phylum Chlorophyta (Green Algae) - The green algae include unicellular and multicellular algae. They are found mostly fresh water. They have cell walls made of cellulose and pectin. Example: Spirogyra - it is a unicellular green alga, it grows as a green thread or filament.
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• Phylum Rhodophyta (Red Algae) - Red algae are mostly large and multicellular. They grow in oceans. The algae 'Nori' and Gelidium are used as food, in parts of Asia. Carragean and agar are glue-like substances in red-algae. Agar is used as a medium used for growing bacteria and other organisms under laboratory conditions.
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• Phylum Phaeophyta (Brown Algae) - Brown algae are multicellular. They grow on rocks in shallow water of the sea. Large brown algae are called kelps and they may grow densely in the sea and form kelp forests. They form important food sources for fish and invertebrates. The brown algae growing on rocks are known as rockweed. Example of rockweed is Sargassum. The brown algae growing on rocks are known as rockweed. Example of rockweed is Sargassum.
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• Phylum Chrysophyta (Golden algae) 'Chryso' means 'color of gold'. There are three types of golden-algae: yellow-green algae, golden brown algae, diatoms. Diatoms are the most abundant and are found in seawater and freshwater habitats. They are major source of food to many aquatic organisms.
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• Phylum Pyrrophyta (Fire Algae) - It contains of species of one-celled algae called dinoflagellate which means 'spinning swimmers'. They store food in the form of starch and oils. The red color is due to chlorophyll a and c and xanthophylls. These organisms have ability of bioluminescence.
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• Fungus-like Protists Slime Molds - Slime molds are saprophytic protists. They are very bright in appearance. They live in moist soil, decaying plants and trees. They are single-celled organisms. During favorable condition they form multi-cellular aggregations called plasmodium. During unfavorable conditions, plasmodia differentiate to form fruiting bodies bearing spores at the tip. These spores posses resistant true walls, which help in survival for a long time during adverse conditions. These spores disperse by air currents.
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Kingdom Protista Examples Green algae - Spirogyra, Ulva, Chlamydomonas, Volvox. Red algae - Porphyra, Rotalgen. Brown algae - Laminaria, Nereocystis. Water molds - Saprolegnia. Phylum Ciliata - Paramecium, Vorticella. Phylum Dinoflagellata - Ceratium, Gonyaulax. Phylum Mastigophora - Trypanosoma, Trichonympha. Phylum Sarcodina - Amoeba.
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The Kingdom
Fungi.
This kingdom consists of fungus & yeasts members. Mycology is a branch of biology which deals with the study of fungi. The organisms in kingdom fungi include mushrooms, yeasts, molds etc. The fungi constitute an independent group to that of plants and animals. They live everywhere in air, in water, on land, in soil, in plants and in animals. Some fungi are microscopic and other extend for more than a thousand acres. 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. They break down organic materials to obtain food. Fungi are in a wide variety of sizes and forms and have great economic importance. Examples of different types of fungus include: Saccharomyces cerevisiae (Yeast) Amanita muscaria (Fly Agaric).
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The 5 Kingdoms of Classification
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 Somali National University
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• • • • • • • •
Kingdom Plantae Characteristics 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. 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 defense 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. Examples of kingdom Plantae This kingdom includes all types plants like herbs, shrubs, trees, creepers, climbers, aquatic plants, desert plants, mountain plants, flowering and non flowering plants, etc Based on their classification, plants are divided into the four main groups. These classifications was 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. Somali National University
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• Kingdom Plantae Classification Plants are classified using the same tools as other organisms, but the largest group after kingdom is called a division (instead of phylum). • To make it easier to study some of the major divisions of plants, the Kingdom Plantae is usually split into two groups: vascular plants and non-vascular plants. The vascular plants are divided again into groups according to the way they reproduce: seedless plants and seeded plants. Then the plants with seeds are divided into gymnosperms and angiosperms. Finally, the angiosperms are divided into the monocots and the dicots.
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Kingdom Plantae
Phylum Rhdophyta (Red algae) Outer cells contain red pigments, so it is called red algae e.g Polysiophonia
Phylum Phaeophyta (Brown algae) they contain brown pigments so, they are called brown algae
Phylum Chlorophyta (Green algae) they have green plastides, so they are called green algae – cell wall contains cellulose
Phylum Bryophyta (Non vascular plants). Most of them are terrestrial plants which grow in damp places
Class Filicatae They don’t form flowers
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Phylum Tracheophyta (vascular plants)
Class Conifers(Gymnosp ermae) They have reproductive organs called cones
Class Angiospermae (produce flowers which form seeds)
Sub-class Monocotyledons.
Sub-class Dicotyledons.
e.g. rice, maize wheat
e.g. cotton, beans
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• Phyllum Bryophyta
They are non-vascular land plants. 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.
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• Phyllum Pteridophytae • 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 pteridophytae e.g.: horsetails, ferns and club mosses.
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• • • • • • • •
Phyllum Angiosperms Angiospermae contains two main classes: Class Monocotyledones (the “monocots”) and Class Dicotyledones (the “dicots”). 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.
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The world's major crops are flowering plants. (a) Rice, (b) wheat, and (c) bananas are monocots, while (d) cabbage, (e) beans, and (f) peaches are dicots Somali National University
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Kingdom,
Animalia
• Animalia consists of Humans and ALL
animals, also known as Metazoa. This kingdom does not contain prokaryotes. All the members of this kingdom are multicellular and lack cell wall, 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. Somali National University
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General characteristics of the Kingdom Animalia are as follows:
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Animals are eukaryotic, multicellular and heterotrophic organisms.
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They have multiple cells with mitochondria and they depend on other organisms for food.
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Habitat - Most of the animals inhabit seas, fewer are seen in fresh water and even fewer on land.
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Cell structure - The animal cell contains organelles like the nucleus, mitochondria, Golgi complex, ribosomes, endoplasmic reticulum, lysosomes, vacuoles, centrioles, cytoskeleton.
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Animals are made up of many organ systems, that aids in performing specific functions that are necessary for the survival of the organism.
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Organ systems are skeletal system, muscular system, digestive system, respiratory system, circulatory system, excretory system, reproductive system, immune system and the endocrine system.
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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 animals skin is 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. 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. Somali National University
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Kingdom Animalia Classification
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Phylum Porifera - They are primitive organisms, most of them are salt-water sponges. They do not have organs or nerve cells or muscle cells. Example: Sycon, Euspongia, Spongilla.
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Phylum Coelentrata (Cnidaria) - This group is composed of jelly-fish and other lower aquatic animals. Example: Aurelia, Adamsia.
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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.
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Phylum Aschelmeinthes - It is a group of round worms, most of them are parasites. This phylum consists of more parasitic worms.
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Phylum Annelida - They are present in aquatic, terrestrial and are free-living or parasitic in nature. This phylum comprises of segmented worms. Example: Earthworm.
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Phylum Arthropoda - This is the largest phylum which consists of insects. Example: Locusts, Butterfly, Scorpion, Prawn.
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Phylum Mollusca - It is the second largest phylum. They are terrestrial and aquatic. Example: Pila, Octopus.
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Phylum Echinodermata - This consists of sea stars and sea urchins. Example: Asteria, Ophiura.
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Phylum Chordata - Animals of this phylum have a characteristic feature of presence of notochord, a dorsal hollow nerve cord and paired pharyngeal gill slits. This group is called vertebrates which include fish, amphibians, reptiles, birds and mammals. Somali National University
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1- Phylum Porifera •
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This phylum includes the sponges and are the simplest of all animals. They have no brain, nerves or gut. Most are found in the ocean. They have pores in their body walls so that water can enter and they can filter feed.
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2- Phylum Cnidaria • This phylum include things like Jellyfish, Hydra, and Sea Anemones. They are more complex than sponges. They have a body cavity and a mouth but have few organs and tissues. • They have tentacles that sting • Reproduction = Both Sexual and Asexual Somali National University
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3- Phylum Platyhelminthes • This includes flat worms. They have a head and a gut and even eyes. Examples include flukes and tapeworms. • They have flattened bodies • Reproduction = Mostly Sexual (two parents)
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4- Phylum Nematodes •
This group includes parasite type round worms. They are very tiny and round. They help break down dead animals and plants to build soil. They have a get and a very simple brain. They are parasites (meaning live on and in other things) and can infect humans. Some of the more popular forms are pin worms and hook worms. • These are cylinder (round) shaped worms • Reproduction = Mostly Sexual (two parents)
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5- Phylum Annelida • • • •
(Annelida, from Latin anellus, "little ring") These include segmented worms. They have a more advanced nervous system and gut than the more simple invertebrates Bodies are made of identical repeating segments Reproduction = Mostly Sexual (two parents)
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6- Phylum Mollusca • This group includes snails, clams and squid, oysters and more. They have the most advanced nervous system of all invertebrates. • They have soft bodies and some are covered by a shell.
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REVIEW
Classification means the act of grouping living things by using a set of rules and similarities. Taxonomy is the field of biology that study how living things are classified. The modern classification system was developed by Carolus Linnaeus. His system is based upon classifying organisms according to physical and structural similarities. Binomial Nomenclature is a two word classification naming system. Each species of a living this is give a double name. First name (Genus) is ALWAYS capitalized. The second name (Species) is NEVER capitalized. Organisms are ranked in a “Taxa� according to their characteristics. Taxa is a further broken-down level of classification found within each kingdom according to similarities. The broader the Taxa the more general its characteristics & the more species it contains. 53
REVIEW (Cont’d) Broadest Level
There are 7 levels in the classification system
Most Specific
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REVIEW (Cont’d) The 5 Kingdoms
Monera – all bacteria Protista – all simple eukaryotes (multi-cellular organisms, i.e. molds) Fungi – all fungus and yeasts (i.e. mushrooms) Plantae – all plants Animalia – all animals, reptiles, insects, birds and fish. Taxonomic Key / Dichotomous Key) is a paired statements that describe the physical characteristics of different organisms 55