Introduction to Animal Taxonomy

Introduction to Animal Taxonomy

• Animal taxonomy is the branch of zoology focused on identifying, describing, naming, and classifying animals.
• Currently, over one million animal species are known.
• A system for naming and categorizing these animals is needed to facilitate study and demonstrate relationships.

Early Classification Attempts

• Aristotle (384-322 BCE) was an early scientist who attempted classifying living organisms.
• Aristotle categorized animals based on the presence or absence of "red blood."
• Other classification methods were based on environment (terrestrial, aquatic, aerial) or diet (carnivorous, herbivorous).

17th Century Advancements

• John Ray (1627-1705) developed a more structured approach to animal classification.
• Ray created a definition of the species, the fundamental unit in classification.
• Modern species are defined as groups sharing similar morphology and that freely interbreed but typically do not interbreed with other species.

Linnaeus's System

• Carl Linnaeus (1707-1778) created a foundational system of classification.
• Linnaeus is famed for his system of binomial nomenclature.
• Each organism is given a two-part name (genus and species, e.g., Homo sapiens).

Modern Classification

• Modern classification considers biochemical, genetic, anatomical, embryological, and physiological data.
• Shared characteristics place species within groups like genera, families, orders, classes, and phyla (higher-level groups).
• Organisms are classified based on common traits and similarities.
• Classification structures like Subkingdoms(e.g., Protozoa, Parazoa, Metazoa) represent a hierarchical classification.

Subkingdom Protozoa

• Protozoa are unicellular, found in diverse habitats.
• They are often microscopic and extremely diverse.
• Most protozoa have a single nucleus.

Subkingdom Parazoa

• Parazoa are multicellular, relatively simple.
• Sponges (Porifera) are the only phylum in this subkingdom.
• Sponges lack true tissue differentiation.

Subkingdom Metazoa

• This subkingdom contains the remaining animal phyla.
• Metazoa exhibit complex tissues and organ systems.
• Different metazoan phyla demonstrate increasing complexity.

Animal Kingdom Classification: Key Concepts

• Modern taxonomy uses a combination of morphological and physiological characteristics to classify organisms.
• Features like cell structure (e.g., unicellular vs multicellular), tissue differentiation, and organ systems are fundamental to classification.