Animal Kingdom: Basis Classification
Classification of the Animal Kingdom is based on the possession of certain key characteristics such as bilateral body symmetry, notochord, segmentation, and coelom. The Animal Kingdom chapter in Biology deals with the taxonomy of the animal kingdom, grouping animals according to common characteristics and relationships during evolution. The basis of classification into the animal kingdom should be grasped through their studies by students, especially for entrance exams like NEET and JEE where questions on animal kingdom taxonomy are very common. These would improve academic performance and appreciation for the diversity of life within the animal kingdom.
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Basis Of Classification Of Animal Kingdom
The animal classification kingdom is a fundamental aspect of biology that organizes animals into hierarchical categories based on shared characteristics and evolutionary relationships.In the animal classification kingdom, organisms are grouped into various phyla, such as Chordata for vertebrates and Arthropoda for invertebrates, to reflect their distinct anatomical and physiological traits. The levels mentioned for the basis of classification of animal kingdom are as described below:
Levels Of Organisation
Every single animal in the animal kingdom is multicellular. However, the degree of cell organisation varies among different animals. Animals can range from basic cell aggregations to complex cell arrangements that give rise to tissues and organs.
Level of Organization | Description | Examples |
|---|---|---|
Cellular Level | Animals with loosely organized cells where each cell is responsible for all life functions, including breathing, nutrition, and excretion. | Porifera (e.g., Sponges) |
Tissue Level | Groups of similar cells perform specific functions; certain metabolic activities are carried out by designated tissues, such as those for digestion or respiration. | Coelenterates and Ctenophores |
Organ Level | Groups of tissues that work together to perform specific functions; specialized organs are present for various purposes like respiration, digestion, and excretion. | Platyhelminthes and Aschelminthes |
Organ System Level | More complex arrangements where organs form systems to perform specific physiological functions; each system is dedicated to a particular function. | Arthropods, Echinoderms, Chordates |
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Animal Kingdom Taxonomy
Taxonomy in the Animal Kingdom also classify animals on a similar hierarchy basis as follows: phylum, class, order, family, genus, and species.
- Animal kingdom taxonomy is understood by biologists as it contributes towards the determination of species for easy identification and naming, communication and research across scientific disciplines.
- Taxonomy in the animal kingdom categorizes organisms into major phyla, such as Chordata, all vertebrates, and Arthropoda, all invertebrates, truly indicating their evolutionary relationship.
- The advances in genetic studies have provided new mileage for Animal kingdom taxonomy: The classifiers can now make more accurate classifications based on the degrees of similarities and dissimilarities among genes as compared to morphological features.
- It would be better if the educational resources on animal kingdom taxonomy had interactive tools and diagrams that could be used to illustrate relationships with different groups of animals and discern their diversity.
Symmetry
If a figure can be split into two equal halves, it is said to be symmetrical. Animals can have radial symmetry, bilateral symmetry, or asymmetry.
Type of Symmetry | Description | Examples |
|---|---|---|
Asymmetry | Animals with nearly asymmetrical shapes; no plane can divide the body into two equal parts. | Sponges |
Bilateral Symmetry | Only one plane can divide the body into two identical halves; most animals exhibit this type of symmetry. | Annelids, Arthropods, Molluscs, Echinoderms, Hemichordates, Chordates (note: echinoderms can show bilateral or radial symmetry depending on development stage) |
Radial Symmetry | The body can be divided into identical halves by any plane passing through the central axis; appears circular from any angle. | Coelenterates, Ctenophores, Echinoderms |
Germinal Layers
The layers of cells in an embryo are called germinal layers. These layers are known as the germinal layers because they are where many organs originate or germinate. Organs can develop from endoderm, mesoderm, or ectoderm, depending on the kind.
Type | Description | Examples |
|---|---|---|
Diploblastic | Animals with cells organized into two embryonic layers: ectoderm and endoderm. A non-differentiated layer called mesoglea lies between them. | Coelenterates, Ctenophores |
Triploblastic | Animals with cells organized into three embryonic layers: ectoderm, mesoderm, and endoderm. | Platyhelminthes, Annelids, Arthropods, Chordates |
Coelom
Different animals may or may not have a coelom or body cavity. Mesoderm lines the coelom. Animals are divided into three groups based on this feature.
Type | Description | Examples |
|---|---|---|
Coelomates | Animals that possess a true body cavity (coelom) lined by mesoderm. | Molluscs, Arthropods, Chordates |
Pseudocoelomates | Animals with a false cavity (pseudocoelom) that is not lined by mesoderm; have patches of mesoderm. | |
Acoelomates | Animals that lack a true body cavity (coelom). | Platyhelminthes |
Segmentation
In certain species, the body is segmented both internally and externally, with at least some organs repeated serially. For instance, the body of an earthworm has a pattern known as metameric segmentation.
Eg: Annelids
Notochord
On the dorsal side of the animal is a rod-shaped structure called a notochord. The notochord originates from the embryo's mesoderm and is mesodermally generated. In most animals, the notochord forms during embryonic development and vanishes later. Even in later phases in some species, it could still be rudimentary. Animals are classified as chordates if a notochord is present. Non-chordate refers to an animal lacking a notochord, such as echinoderms and Porifera. The notochord is a structure seen in hemichordates and chordates.
Different Phyla of Animal Kingdom
The animal kingdom classification system organizes living organisms into hierarchical categories, starting from broad groups like kingdoms and phyla down to specific species. In animal kingdom classification, animals are divided into various phyla based on their body structure, reproductive methods, and genetic relationships, with Chordata and Arthropoda being two of the largest groups. Advances in molecular biology have significantly impacted animal kingdom classification, allowing scientists to refine classifications based on genetic data rather than solely on physical traits. They progress from the most basic to the most complex in the chart classifying animals. The animal kingdom is classified into 11 different phyla namely: Porifera, Coelenterata, Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata and Chordata. Understanding animal kingdom classification is essential for biologists as it provides a framework for studying the diversity of life and the evolutionary relationships among different species.
Phylum | Common Name | Characteristics | Examples |
|---|---|---|---|
Porifera | Sponges | - Basic multicellular animals - Bodies covered with pores (Ostia) - Canal system for circulation of water and nutrients - Supported by spicules - Minimal tissue differentiation | Spongilla, Sycon |
Coelenterata | Cnidaria | - More body differentiation - Single opening for ingestion and egestion - Diploblastic with two germ layers - Can live solitary or in colonies | Jellyfish, Sea Anemones, Hydra |
Ctenophora | Comb Jellies | - Marine animals - Radially symmetric and diploblastic - Bioluminescent - Eight rows of ciliated comb plates for locomotion | Pleurobrachia, Ctenoplana |
Platyhelminthes | Flatworms | - Dorsoventrally flattened bodies - Triploblastic with three germ layers - Acoelomates with bilateral symmetry - Presence of flame cells for excretion | Planaria, Liver Fluke, Tapeworm |
Aschelminthes | Roundworms | - Triploblastic and bilateral symmetry - Cylindrical body shape - Pseudocoelomates (no true coelom) - Complete alimentary canal | Ascaris, Wucheria |
Annelida | Segmented Worms | - Found in various environments (land, freshwater, marine) - Triploblastic and bilaterally symmetrical - True coelomates with segmented bodies | Earthworms, Leeches |
Arthropoda | Jointed-Legged Animals | - Largest phylum in the animal kingdom - Body divided into head, thorax, abdomen - Open circulatory system - Chitinous exoskeleton | Crabs, Spiders, Mosquitoes |
Mollusca | Molluscs | - Second-largest animal phylum - Coelomate and bilaterally symmetrical - Organ-system level organization - Presence of radula for feeding | Octopus, Snails, Mussels |
Echinodermata | Spiny-Skinned Animals | - Marine animals with calcareous endoskeletons - Triploblastic with a coelomic cavity - Radial symmetry in adults but bilateral in larvae | Starfish, Sea Urchins |
Hemichordata | Acorn Worms | - Marine animals resembling worms - Triploblastic and bilaterally symmetrical - Open circulatory system | Balanoglossus, Saccoglossus |
Chordata | Chordates | - Presence of notochord, dorsal hollow nerve cord, paired pharyngeal gill slits - Coelomate with organ-system level organization | Amphioxus (Lancelet), Ascidia (Urochordata) |
The animal classification kingdom has evolved over time, with advancements in genetic research leading to the re-evaluation of certain classifications based on molecular data rather than just physical characteristics.
Tips, Tricks, and Strategies to Prepare for Classification Of Animal Kingdom
To effectively study the Animal Kingdom: Basis Classification, consider these strategies:
Tips and Tricks | Mnemonic |
|---|---|
Understand the key phyla and their characteristics. | PANDA (Porifera, Annelida, Nematoda, Dorsal, Arthropoda) |
Use diagrams to visualize the classification hierarchy. | DIAGRAM (Draw Illustrations for Great Analysis of Relationships in Morphology) |
Practice with flashcards for quick recall of phyla examples. | FLASH (Flashcards Lead to Active Study Habits) |
Group study sessions can enhance understanding through discussion. | TEAM (Together Everyone Achieves More) |
Educational materials on the animal classification kingdom often include charts and diagrams that illustrate the relationships among different animal groups, making it easier for students to grasp the concept of biodiversity.
Weightage of Classification Of Animal Kingdom in Different Entrance Exams
Knowing the weightage of this topic helps prioritize your study efforts. Here’s how it is weighted across various entrance exams:
Entrance Exam | Weightage (%) |
|---|---|
5-10% | |
3-5% | |
4-6% | |
6-8% | |
2-4% |
Types of Questions Asked on Classification Of Animal Kingdom in Different Exams
Familiarizing yourself with the types of questions can help you prepare more effectively. Here’s a summary of the types of questions that may be asked across various exams:
Entrance Exam | Types of Questions |
|---|---|
NEET | Conceptual questions, matching examples |
JEE Main | Multiple-choice questions, classification tasks |
JEE Advanced | Analytical problems, comparative analysis |
AIIMS | Short answer questions, application-based queries |
UPSC | Descriptive questions, analytical essays |
By utilizing these tips and understanding the exam weightage and question types, you can enhance your preparation for the topic of Classification Of Animal Kingdom. Understanding the animal classification kingdom helps scientists communicate effectively about different species, as it provides a standardized framework for identifying and naming animals.
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Frequently Asked Questions (FAQs)
Heterotrophic nutrition is the type of nutrition in which an organism depends on plants or other living things for nourishment since it is unable to manufacture its own food.
The repeating of similar bodily parts is known as metamerism. Metamerism is also called segmentation. The Annelids, which include earthworms, leeches, and tubeworms exhibit this sort of development. Additionally, Arthropods, which include crustaceans, insects, etc exhibit it in a more developed form.
Pseudocoelom is the characteristic feature of the phylum Aschelminthes.
The characteristic features of all chordates are:
Presence of notochord.
Presence of dorsal nerve cord.
Triploblastic.
Post anal tail is present
Pharyngeal slits are present.
The basis of classification has made it simpler to study animals. Learning about organisms and comparing one set of animals to another for a better understanding are becoming simpler.
The major classifications of the animal kingdom include various phyla, such as Porifera, Coelenterata (Cnidaria), Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, and Chordata.
The 7 classifications of animals are:
- Kingdom
- Phylum (or Division)
- Class
- Order
- Family
- Genus
- Species
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