Taxonomy

• Taxonomy


  The science of classifying and naming living organisms based on shared characteristics and evolutionary relationships

  
• Taxonomy


  • Involves the identification, description, naming, and classification of organisms into hierarchical categories
  • The primary goals are to organize and categorize the vast diversity of life on Earth, providing a systematic and standardized way to communicate about different species

  
• Key components of taxonomy

  • Classification
  • Nomenclature
  • Identification
  • Description
  • Evolutionary relationships

  
• Classification


  The process of arranging organisms into hierarchical groups based on shared characteristics. The hierarchical levels include domain, kingdom, phylum, class, order, family, genus, and species

  
• Nomenclature


  The system of assigning names to organisms. Binomial nomenclature, introduced by Carl Linnaeus in the 18th century, is the widely accepted practice of giving each species a two-part Latinized name (genus and species)
• Identification

  The process of recognizing and assigning an organism to a known taxonomic group based on its characteristics. This involves comparing the observed traits of an organism with those described in taxonomic keys or identification guides

  
• Description


  Providing detailed information about the characteristics of a newly discovered or studied organism, helping to distinguish it from others
• Evolutionary relationships


  Modern taxonomy often incorporates information about the evolutionary relationships among organisms. Molecular biology, genetic analysis, and other advanced techniques play a crucial role in understanding the evolutionary tree of life

  
• Classification makes the study of organisms much easier, as there are millions of lifeforms and we cannot study them one by one. We can study the different classes or groups much easier after classifying them
• Characteristics considered for classification of living organisms

  • Whether they are made of prokaryotic or eukaryotic cells
  • Whether the cells occur singly or they are grouped together and live as an invisible group
  • Whether they produce their own food by photosynthesis or get their own food from outside
  • Of the organisms which produce their own food (plants) what is the level of organization of their body
  • Of the animals what is the level of organization of their body and what are their special organs and their functions
• The five kingdoms of Whittaker's classification

  • Monera
  • Protista
  • Fungi
  • Plantae
  • Animalia

  
• Hierarchy of classification


  • Kingdom
  • Phylum (for plants) / Division (for animals)
  • Class
  • Order
  • Family
  • Genus
  • Species
• Broadly, a species includes all organisms that are similar enough to breed and perpetuate
• Binomial nomenclature


  Assigning two names to a particular species, with the first name being the genus and the second name being the species
• Binomial nomenclature was first proposed by Carolus Linnaeus, who is known as the Father of Taxonomy
• Conventions for writing scientific names

  • The name of the genus begins with a capital letter
  • The name of the species begins with a small letter
  • When written by hand, the genus and the species are underlined separately
  • When printed, the scientific names are written in italics
• Rules for nomenclature


  • Each organism has a distinct scientific name having a genus and species
  • The generic and specific words should not have less than three letters or more than 12 letters
  • The generic name is written first, like a noun, and its first letter is always capital
  • The specific word is written after the generic name, and it starts with a small letter
  • The name of the discoverer is appended to the two-word scientific name either in full or abbreviated form
  • Scientific names are printed in italics, and hand-written names are underlined
  • When an organism has been given different scientific names by different workers, the "law of priority" is followed, and the old valid name is accepted
• Examples of classification


  • Mango (Mangifera indica)
  • Lion (Panthera leo)
• The three domains of life

  • Archaea
  • Bacteria
  • Eukarya

  
• Archaea (Archaebacteria)


  Resemble the first life forms on Earth, are primitive, and able to live in extreme conditions (thermophiles, halophiles, acidophiles, alkaliphiles, methanogens)
• Bacteria (Eubacteria)

  The largest group of Monera, including the majority of bacteria, most of which are decomposers, heterotrophs, or saprophytes, while some photosynthesize or chemosynthesise

  
• Characteristics of Monera

  • Unicellular and prokaryotic
  • Lack a true nucleus and membrane-bound organelles
  • Some have a cell wall (bacteria and cyanobacteria), while others don't (mycoplasma)
  • Have autotrophic or heterotrophic nutrition
• Characteristics of Protista

  • Unicellular and eukaryotic
  • Have a true nucleus
  • Microscopic organisms
  • Have structures like cilia, flagella, and pseudopodia for locomotion and food capture
• Characteristics of Fungi

  • Heterotrophic and eukaryotic
  • Mainly multicellular, with the exception of yeast
  • Have a cell wall made of chitin
  • Have saprophytic (decomposer) nutrition
• Characteristics of Plantae

  • Eukaryotic and multicellular
  • Have an additional covering on the plasma membrane called the cell wall, made of cellulose
  • Have chlorophyll pigments for photosynthesis
  • Have vascular tissues (xylem and phloem) for transport
  • Are non-motile or static
• Characteristics of Animalia

  • Eukaryotic and multicellular
  • Heterotrophic (have heterotrophic nutrition)
  • Lack a cell wall and chlorophyll
  • Generally have locomotory organs and are motile
  • Have a well-developed sensory and neuromuscular system
• The five phyla of the Plant Kingdom

  • Thallophyta
  • Bryophyta
  • Pteridophyta
  • Gymnosperms
  • Angiosperms

  
• The ten divisions of the Animal Kingdom

  • Porifera
  • Coelenterata (Cnidaria)
  • Platyhelminthes
  • Nematoda (Aschelminthes)
  • Annelida
  • Arthropoda
  • Mollusca
  • Echinodermata
  • Protochordata
  • Vertebrata (Cyclostomata, Pisces, Amphibia, Reptilia, Aves, Mammalia)

  
• Prototrophs


  • Do not have cell wall and chlorophyll pigments
  • Generally have locomotory organs and are motile
  • Have a well developed sensory and neuromuscular system
• Prototrophs contain all invertebrates and vertebrates
• Animal kingdom divisions


  • Porifera
  • Coelenterata (Cnidaria)
  • Platyhelminthes (flat worms)
  • Nematoda (Aschelminthes)
  • Annelida (segmented worms)
  • Arthropoda (animals with joined legs)
  • Mollusca (soft)
  • Echinodermata (spiny skinned animals)
  • Protochordata
  • Vertebrata
• The animal kingdom is further classified based on the extent and type of the body design differentiation found
• Porifera


  Pores having animals
• Porifera


  • Diploblastic and not well-differentiated
  • Marine habitat
  • Non-motile (stable)
  • Have a canal system to circulate water
  • Have a hard outside layer or skeleton
• Porifera


  • Spongilla, Sycon, Euplectela
• Coelenterata (Cnidaria)


  Organisms with tentacles
• Coelenterata (Cnidaria)


  • Aquatic (mostly marine) habitat
  • Body made by two layers of cells
  • Have a gastrovascular cavity
  • Found in medusae and polyps forms
• Coelenterata (Cnidaria)


  • Jellyfish, Sea anemones, corals, hydra
• Platyhelminthes


  • Flattened dorsiventrally
  • Bilaterally symmetrical
  • Triploblastic
  • No true coelom
  • Found as free-living or parasitic
• Platyhelminthes


  • Planarians, Liver flukes, Tapeworm