Classification and Taxonomy

Jul 20, 2024

Classification and Taxonomy

Introduction

  • Hydra: Small freshwater animal (a few millimeters in length).
    • Attack and eat tiny prey.
    • Reproduce by budding identical offspring.
    • Misleading appearance; categorized as an animal.

Classification Overview

  • Taxonomy: Naming and classification of species.
  • Carl Linnaeus: Key figure in formal classification (18th century).
  • Historical context: No categories for protists, bacteria; lacked knowledge of DNA and cell structures.
  • Modern classification: Advances in DNA knowledge continue to refine organism classification.

Hierarchical System

  • Mnemonic: "Dear King Paramecium Cares Only For Green Spirulina"
  • Hierarchy Levels:
    1. Domains
    2. Kingdoms
    3. Phylum
    4. Class
    5. Order
    6. Family
    7. Genus
    8. Species

Domains

  • 3 Domains: Bacteria, Archaea, Eukarya.
  • Bacteria:
    • Prokaryotes with varied functions (disease-causing, digestive, decomposing, nitrogen-fixing).
  • Archaea:
    • Prokaryotes with significant DNA and structural differences from bacteria.
    • Often extremophiles (extreme salt, no oxygen, high temperature environments).
    • Example: Methanogens (live in low-oxygen areas, produce methane).
  • Eukarya:
    • Eukaryotes with common eukaryotic characteristics.

Kingdoms

  • Changing organization: No universal agreement among scientists.
  • Differences in systems: 5-kingdom vs 6-kingdom systems.
  • Eukaryotic Kingdoms:
    • Protista:
      • Diverse; sometimes considered for further division.
      • “Animal-like,” “plant-like,” and “fungi-like” protists.
      • Include both autotrophs and heterotrophs; can be unicellular or multicellular.
    • Fungi:
      • Heterotrophs (e.g., athlete’s foot fungus).
      • Usually multicellular; cell walls of chitin.
    • Plantae:
      • Autotrophs (e.g., carnivorous plants).
      • Multicellular; cell walls of cellulose.
    • Animalia:
      • Mostly multicellular, heterotrophic (includes hydra).

Binomial Nomenclature

  • Developed by Carl Linnaeus: Two-part naming system using Latin or Greek.
  • Scientific names:
    • Genus: Capitalized and italicized (e.g., Homo).
    • Species: Lowercase and italicized (e.g., sapiens).
  • Importance: Universal and specific identification across different regions (e.g., mountain lion = puma, cougar, Texas Panther).

Conclusion

  • Scientific names: Enable precise communication and classification of organisms.
  • Encouragement: Stay curious!