Animal Taxonomy and Systematics

Systematic Zoology/Animal Taxonomy

• Is the branch of zoology that focuses on identifying, describing, naming, and classifying animals.
• Includes understanding the relationships between different animal types.
• Origins of the term "systematics" come from the Latinized Greek word "systema," meaning "to put together."
• Linnaeus used the term "systematics" in the 4th edition of his book "Systema Naturae" in 1735.
• Simpson (1961) defined systematics as the scientific study of the diversity of organisms and their relationships.

Early Animal Classification

• Aristotle (384-322 BCE) was an early zoologist and attempted to classify animals.
• His classification was based on observable characteristics like blood presence and birth method.
• He categorized animals into aquatic, terrestrial, and aerial groups.

Linnaean System of Classification

• Carl Linnaeus (1705-1778) developed the classification system commonly used today.
• His system employs binomial nomenclature (Genus species).
• Genus categorizes animals sharing many similar characteristics.
• Species categorizes animals with similar characteristics capable of interbreeding.

Hierarchy of Classification

• The classification system is hierarchical, starting with the most inclusive kingdom and progressing to less inclusive categories down to species..
• The hierarchy includes Kingdom, Phylum, Class, Order, Family, Genus, and Species (sub categories are also employed)
• Using Latin is essential in the naming of animal species.

Protozoa Classification

• Protozoa are single-celled organisms.
• They are classified into Subkingdom Protozoa, with four subphyla based on locomotion: Mastigophora (flagella), Sarcodina (pseudopodia), Ciliophora (cilia), and Sporozoa (no locomotion).
• Protozoa can be unicellular or acellular, with a single protoplasmic mass.

Animal Kingdom: Protozoa Characteristics

• Size: Typically microscopic, ranging from 2-3 µm to 16 mm. Some are visible to the naked eye.
• Structure: Single nucleus (often with endosomes), distinctive ectoplasm, and endoplasm.
• Water Balance (osmoregulation): Contractile vacuoles remove excess water (common among water-dwelling protozoa).
• Habitat: Solitary or colonial, some are free-living, and others are parasitic.
• Reproduction is both asexual (binary fission, multiple fission, and budding) or sexual (fusion of gametes)
• Some Protozoa are harmful and cause diseases (e.g., Trypanosoma) while others are helpful as they can eat harmful bacteria (e.g., Paramecium) and serve as food for other animals.
• Digestion occurs intracellularly within food vacuoles.
• Respiration takes place by diffusion through the body surface. Some can respire without oxygen, and others die exposed to oxygen.
• Excretion occurs by the diffusion of waste products across the body surface.
• Some protozoans are harmful to humans, causing diseases like Trypanosomiasis.
• Others are helpful because they eat harmful bacteria.
• Protozoans reproduce asexually through binary fission, multiple fission and budding.
• They can also reproduce sexually through gamete fusion.

Amoeba Classification

• Amoeba belongs to the Subkingdom Protozoa, Phylum Protozoa, Subphylum Sarcodina, and Class Amoebozoa .
• Characterized by locomotion using pseudopodia.
• Amoeba exhibits different forms based on the locomotion.

Entamoeba: General Information

• Entamoeba includes the species such as Entamoeba histolytica (pathogenic) and Entamoeba coli (non-pathogenic)
• The parasitic Entamoeba histolytica and the non-pathogenic Entamoeba coli are part of the Class Zoomastigophora.
• Transmission through ingestion of food or water contaminated with fecal matter.
• Prevention through improved hygiene is vital.