Biology: Classification of Living Beings

Classification of Living Beings

Historical Background

• Classification of living beings has been practiced since ancient times
• Aristotle (384-322 BCE) and Carl Linnaeus (1707-1778) made significant contributions to the field

Types of Classification

• Artificial System: Based on visible characteristics, such as shape and size
• Natural System: Based on evolutionary relationships and common ancestors

Major Classification Ranks

1. Domain: Highest level of classification, includes Archaea, Bacteria, and Eukarya
2. Kingdom: Second highest level, includes Monera, Protista, Fungi, Plantae, and Animalia
3. Phylum (or Division in Plantae): Level below kingdom, includes Chordata, Arthropoda, etc.
4. Class: Level below phylum, includes Mammalia, Aves, etc.
5. Order: Level below class, includes Carnivora, Passeriformes, etc.
6. Family: Level below order, includes Felidae, Canidae, etc.
7. Genus: Level below family, includes Panthera, Canis, etc.
8. Species: Most specific level, includes Homo sapiens, Felis catus, etc.

Binomial Nomenclature

• Developed by Carolus Linnaeus
• Each species has a unique two-part name consisting of:
  • Genus name (capitalized)
  • Species epithet (not capitalized)

Example: Homo sapiens (human species)

Taxonomic Hierarchy

• Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species

Classification of Living Beings

Historical Background

• Classification of living beings dates back to ancient times
• Aristotle and Carl Linnaeus made significant contributions to the field

Classification Systems

Artificial System

• Based on visible characteristics, such as shape and size

Natural System

• Based on evolutionary relationships and common ancestors

Classification Ranks

Domain

• Highest level of classification
• Includes Archaea, Bacteria, and Eukarya

Kingdom

• Second highest level of classification
• Includes Monera, Protista, Fungi, Plantae, and Animalia

Phylum/Division

• Level below kingdom
• Includes Chordata, Arthropoda, etc. in Animalia

Class

• Level below phylum
• Includes Mammalia, Aves, etc.

Order

• Level below class
• Includes Carnivora, Passeriformes, etc.

Family

• Level below order
• Includes Felidae, Canidae, etc.

Genus

• Level below family
• Includes Panthera, Canis, etc.

Species

• Most specific level of classification
• Includes Homo sapiens, Felis catus, etc.

Binomial Nomenclature

• Developed by Carolus Linnaeus
• Each species has a unique two-part name consisting of:
  • Genus name (capitalized)
  • Species epithet (not capitalized)
• Example: Homo sapiens (human species)

Taxonomic Hierarchy

• Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species