18.02 Hierarchical Classification

Importance of Classification

• Purpose: Organizes diverse organisms for easier understanding and memorization.
• Taxonomy:
  • Definition: Study/practice of classification.
  • Method: Assigns organisms into taxonomic units (taxa) forming a hierarchy.

Taxonomic Hierarchy

• Ranked Organization:
  • Species: Base unit; organisms that can interbreed.
  • Higher Ranks: Groups with shared similarities.
    • Genus → Family → Order → Class → Phylum → Kingdom → Domain (highest).
• Example:
  • African Bush Elephant:
    Loxodonta africana
  • Hibiscus:
    Hibiscus rosa-sinensis

Key Features

• Hierarchical Classification:
  • Definition: Groups organisms into increasing levels of inclusivity, starting from species (lowest) to domain (highest).
  • Example: Species grouped into a genus, genera into families, etc.
• Taxonomic Rank:
  • Definition: Levels in the hierarchy (e.g., species, genus, family).
  • Example: Loxodonta africana belongs to genus Loxodonta, family Elephantidae.

Key Terms

• Biological Classification: Systematic grouping of living/extinct organisms based on similarities/differences.
• Taxonomy: Study of classification/naming within hierarchy.
• Hierarchical Classification: Arrangement of organisms into ranks (species → domain).
• Taxonomic Rank: Categories (e.g., genus, family, order) within classification.
• Taxon (Taxa): Any taxonomic group (e.g., species, genus, family).
• Domain: Highest rank.
• Kingdom: Rank below domain.

Question 1

1. Giraffe Classification Table:

2. Explanation:

Taxonomic Rank:

• Level of classification (e.g., genus, family, kingdom).
• Giraffes and elephants share ranks up to class Mammalia, diverge at order.

Hierarchical System:

• Starts with specific (species).
• Progresses to broader categories (domain), grouping related organisms systematically.