Animal Diversity and Classification

Animal Diversity, Classification, and Binomial Nomenclature

• Approximately 1.8 million plant and animal species have been described, with roughly 1.4 million being animals.
• Estimates suggest tens of millions more undescribed species, particularly in challenging environments like the ocean floor.
• The vast number of animal species necessitates specialization within zoology, making it impossible for a single zoologist to be an expert on all species.

Sub-Disciplines of Zoology

• Protozoology: The study of protozoa
• Entomology: The study of insects
• Malacology: The study of mollusks (e.g., snails, octopuses)
• Carcinology: The study of crustaceans (e.g., crabs, shrimps)
• Ichthyology: The study of fishes
• Herpetology: The study of amphibians (e.g., toads, frogs, salamanders, snakes, crocodiles)
• Ornithology: The study of birds
• Mammalogy: The study of mammals

Animal Classification

• Systematics: The branch of zoology that studies the classification and evolutionary relationships of animal groups
• Taxon: A group of organisms that share a set of characteristics
• Taxonomy: Scientific classification of animals
• Systematics: Studying evolutionary relationships among species

Modern Taxonomic Hierarchy (using humans as an example)

• Domain: Eukarya
• Kingdom: Animalia
• Phylum: Chordata
• Class: Mammalia
• Order: Primates
• Family: Hominidae
• Genus: Homo
• Species: sapiens

Binomial System of Classification

• Binomial Nomenclature: The modern, universal system for classifying animals, primarily developed by the Swedish biologist, Carl Linnaeus.
• Animals are classified into a hierarchical structure based on relatedness.
• Binomial name: Each living organism has a two-part name consisting of the genus and species. - The genus name is written first and the species name second. - Both names are always either italicized or underlined (handwritten).
• Each species has a unique binomial name to avoid ambiguity.

Why Use Binomial Names Instead of Common Names?

• Common names vary by region and language.
• A single species can have many different common names, leading to ambiguity.
• Common names can sometimes represent broader taxonomic groups rather than a specific species. This creates a need for clear scientific classification.