Brief Summary
The session introduces the animal kingdom, focusing on its classification and key characteristics. It covers the strata of classification, starting with kingdom and moving down to species, and highlights the importance of understanding the sequence of phyla to grasp evolutionary changes. The lecture also details the five key characteristics used to classify organisms into the animal kingdom: cellular structure, body structure, mode of nutrition, mode of reproduction, and phylogenetic relation.
- The five kingdom classification was given by RH whitetaker.
- Strata of classification: Kingdom, Phylum, Class, Order, Family, Genus, Species.
- Five characteristics to classify organisms into the animal kingdom: cellular structure, body structure, mode of nutrition, mode of reproduction, and phylogenetic relation.
Introduction to Zoology and Animal Kingdom
Dr. Anisha from Sri Chaitanya Educational Institutions welcomes students to a zoology session focusing on the animal kingdom, a basic topic for first-year students. The session aims to simplify the approach to this complex subject, encouraging students to be ready with pen and paper.
Strata of Classification
The five-kingdom classification, given by RH Whittaker, is the base for understanding the animal kingdom. Kingdoms are further classified into phylum, class, order, family, genus, and species. The session focuses on Kingdom Animalia, which is divided into various phyla, each further divided into class, order, family, genus, and species.
Phyla of Kingdom Animalia
Kingdom Animalia is divided into different phyla, and it's important to remember the characteristics of each phylum in sequence to understand the evolutionary pattern. The sequence starts with simpler phyla like Porifera, Coelenterata (also called Cnidaria), Ctenophora, Platyhelminthes, and Aschelminthes, which are the most primitive forms. More complex phyla include Annelida, Arthropoda, and Mollusca, followed by Echinodermata and Hemichordata. The most complex phylum is Chordata, to which humans belong. Remembering the sequence is crucial because it reflects evolutionary changes in digestion, feeding, and body structure.
Basis of Classification
RH Whittaker classified organisms into different phyla based on several characteristics. These include cellular structure (eukaryotic in Animalia), body structure (multicellular), mode of nutrition (holozoic, involving ingestion of food), mode of reproduction (primarily sexual, though asexual reproduction is present in some lower animals), and phylogenetic relation (evolutionary lineage). Phylogenetic relation refers to the evolutionary process of a species, indicating that animals share a lineage distinct from plants or fungi.
Phylum Porifera
Phylum Porifera includes pore-bearing organisms with many pores on their body surface that aid in digestion, respiration, and circulation. Common examples include sponges, also known as earn sponges, bath sponges, and freshwater sponges.
Phylum Coelenterata (Cnidaria)
Phylum Coelenterata, also known as Cnidaria, includes organisms commonly called jellyfishes, hydra, and sea anemones. These organisms may have a cylindrical body attached to a surface with hair-like extensions called tentacles. They often possess a strong toxin for protection or to kill prey. Corals, which form coral reefs, also belong to this phylum.
Phylum Ctenophora
Phylum Ctenophora includes comb jellies, which are transparent, jellyfish-like organisms found exclusively in seawater. They exhibit bioluminescence, emitting light in the dark, similar to fireflies.
Phylum Platyhelminthes
Phylum Platyhelminthes includes flatworms, which are flat like a leaf or sheet of paper. Examples include turbellarians, tapeworms (parasitic), and flukes.
Phylum Aschelminthes
Phylum Aschelminthes includes roundworms, which appear elongated and cylindrical. They are called roundworms because their cross-section appears round under a microscope. Examples include Ascaris, pinworms, hookworms, and giant roundworms, many of which are parasitic.
Phylum Annelida
Phylum Annelida includes annelids, which have ring-like patterns (annuli) on their bodies. Examples include earthworms, leeches, and sandworms.
Phylum Arthropoda
Phylum Arthropoda includes organisms with jointed legs (arthro = joints, poda = leg). Examples include insects, butterflies, spiders, and scorpions. Arthropoda is the largest phylum in the animal kingdom based on the number of species it includes.
Phylum Mollusca
Phylum Mollusca includes soft-bodied organisms, many of which are enclosed in a hard shell. Examples include octopus, sepia, cuttlefish, and various shelled organisms found on sea beaches.
