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Animal Kingdom Animalia Subphylum - An Overview

Animal Kingdom Animalia Subphylum - An Overview

Irshad AnwarUpdated on 02 Jul 2025, 05:23 PM IST

Animals are generally classified into invertebrates and vertebrates. Invertebrates are organisms without a backbone, and include organisms like sponges, worms, insects, and molluscs. The vertebrates have a backbone and include fish, amphibians, reptiles, birds, and mammals. The vertebrates have a well-developed skeletal system and organ systems.

This Story also Contains

  1. Kingdom Animalia: Historical Context
  2. General Characteristics of the Kingdom Animalia
  3. Characteristics of Organisms in the Animal Kingdom
  4. Significance of the Animal Kingdom
  5. Recommended Video On Animal Kingdom Subphylum
Animal Kingdom Animalia Subphylum - An Overview
Animal Kingdom Animalia Subphylum

Understanding the Animal Kingdom helps us to appreciate how different animals adapt, survive, and interact within the environment. The classification is important in biology and useful in fields such as medicine, agriculture and conservation. The animal kingdom is one of the most important topics in biology.

Kingdom Animalia: Historical Context

Kingdom Animalia consists of multicellular, heterotrophic, and eukaryotic organisms. They obtain food from autotrophs (plants) and other animals and nutrition by ingesting plant or animal material.

However, the classification of the kingdom was not an easy task for the scientist. Several changes took place till the final classification came into existence. Some of the historical context regarding animal classification is mentioned below in the table.

Scientist and Year

Classification System

Key Features

Aristotle (384-322 BC)

Two Kingdom Classification

  • Animalia

  • Plantae

  • Based on mobility and habitat, and was based on the simple division of organisms.

Linnaeus (1707-1778)

Binomial Nomenclature

  • The classification was done based on genus and species.

  • It was divided based on the physical traits

Ernst Haeckel (1866)

Three Kingdoms

  • Introduced Protista into unicellular organisms.

  • Classified using metazoans into the same phylum.

Copeland ( 1956)

Four kingdoms classification

  • Monera

  • Protista

  • Fungi

  • Metazoa

  • Fungi were added to a separate Kingdom as they fall into the category of prokaryotic classification.

Whittaker (1969)

Five Kingdoms classification


  • The division was done based on evolutionary relationships between organisms.

  • Prokaryotes and eukaryotes world divided from each other.



Also Read:

General Characteristics of the Kingdom Animalia

All the organisms present in the kingdom Animalia have their specific characteristics. But the overall Kingdom also has some common characteristics which make it fall into this category. Some of the common characteristics of the kingdom Animalia are discussed below:

  • One of the largest kingdoms with more than 8.7 million species.

  • The animal kingdom has different levels of organisms like such as heterotrophic organisms in the same category.

  • Most of the organisms in the animal kingdom have sexual reproduction as their primary mode of reproduction.

  • The cells lack outer cell walls like plants, but some of them also have cell walls present in them.

  • Some of the organisms in the animal kingdom are sensitive to external stimuli.

  • Most of the animals are diploid, which means there are two copies of each gene present.

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Commonly Asked Questions

Q: How do animals obtain and process nutrients?
A:
Animals obtain nutrients by consuming other organisms or organic matter. They digest food internally using specialized organs and enzymes. The digestive system breaks down complex molecules into simpler forms that can be absorbed and used for energy or to build and repair body tissues.
Q: How do animals store and use energy?
A:
Animals store energy primarily as glycogen in muscles and liver, and as fat in adipose tissue. Energy is used for movement, growth, reproduction, and maintaining body functions. The balance between energy intake, storage, and use is crucial for survival and varies among different animal groups based on their lifestyle and environment.
Q: How do animals maintain homeostasis?
A:
Animals maintain homeostasis through various physiological processes and organ systems. This includes regulating body temperature, maintaining water balance, controlling pH levels, and managing energy use. Different animals have evolved diverse strategies to maintain internal stability in varying environments.
Q: How do animals communicate with each other?
A:
Animals communicate through various methods including visual signals (like colorful displays), auditory signals (like bird songs), chemical signals (like pheromones), and tactile signals (like touch). Communication is crucial for finding mates, warning of dangers, establishing territories, and maintaining social structures.
Q: How do animals regulate their body temperature?
A:
Animals regulate body temperature through various mechanisms. Endotherms (like mammals and birds) generate internal heat and maintain a constant body temperature, while ectotherms (like reptiles and amphibians) rely more on external heat sources. Behavioral adaptations, like seeking shade or sunbathing, also play a role in temperature regulation.

Characteristics of Organisms in the Animal Kingdom

Apart from the common characteristics, each of the organisms possesses their characteristics. To characterise them in a better way, they are divided into different phyla, which are discussed below along with their key features.

Phylum

Common

Name

Body Structure

Symmetry

Reproductive

Mode

Examples

Porifera

Sponges

Porous body structure with a heart outer skeleton.

Non-motile

Asymmetrical

Both asexual and sexual

Sycon and Spongilla

CtenophoraComb jelliesSoft, transparent, bioluminescent body with eight ciliated "comb plates" for locomotionBiradial symmetry

Sexual reproduction, external fertilisation


Pleurobrachia, Ctenoplana

Cnidaria

Coelenterates

Presence of hollow body cavity with outer and inner linings.

Radial symmetry

Sexual and asexual


Hydra, jellyfish and corals

Platyhelminthes

Flatworms

Flatten body structure with no internal cavity.

Bilateral symmetry

Sexual and asexual

Tapeworms and Planaria

Aschleminthes

Roundworms

Cylindrical body structure with pseudo cavity

Bilateral symmetry

Mostly sexual

Ascaris and Wuchereria

Annelida

Segmented Worms

Segmented body with cylindrical structure. Presence of true body cavity.

Bilateral symmetry

Sexual and asexual

Earthworms and leeches

Arthropoda

Arthropods

Segmented body with jointed appendages, presence of an exoskeleton.

Bilateral symmetry

Mostly sexual

Mosquito spiders and butterflies

Mollusca

Molluscs

Segmented body with fewer segments and the presence of well-developed organs.

Bilateral symmetry

Sexual and asexual

Snails and octopus

Echinodermata

Echinoderms

The presence of hard skeletal structures that are made of calcium carbonate.

Radial symmetry

Sexual and asexual

Sea Urchins and Starfish

Hemichordata

Hemichordates

Soft body structure with a single layer of epidermis.

Bilateral symmetry

Sexual, external fertilisation

Sea Mammals

Chordata

Chordates

Bilateral symmetry with notochord present at the same stage.

Bilateral symmetry

Sexual

Urochordates and vertebrates

Commonly Asked Questions

Q: What is the Animal Kingdom Animalia?
A:
The Animal Kingdom Animalia is a diverse group of multicellular eukaryotic organisms that are heterotrophic, meaning they obtain nutrition by consuming other organisms. Animals are characterized by their ability to move, reproduce sexually, and respond to stimuli in their environment.
Q: How does the Animal Kingdom differ from other kingdoms of life?
A:
The Animal Kingdom differs from other kingdoms in several ways: animals are multicellular and heterotrophic, lack cell walls, have specialized tissues and organs, and can move voluntarily. Unlike plants, they cannot produce their own food through photosynthesis, and unlike fungi, they digest food internally.
Q: What are the main characteristics that define animals?
A:
The main characteristics that define animals include: multicellularity, heterotrophy, lack of cell walls, ability to move voluntarily, sexual reproduction, embryonic development, and the presence of specialized tissues and organs.
Q: How are animals classified within the Animal Kingdom?
A:
Animals are classified based on their body structure, symmetry, presence or absence of a body cavity, embryonic development, and other characteristics. The main groups include invertebrates (animals without a backbone) and vertebrates (animals with a backbone).
Q: What is the significance of body symmetry in animal classification?
A:
Body symmetry is important in animal classification as it reflects the animal's body plan and internal organization. The main types are radial symmetry (found in cnidarians and echinoderms) and bilateral symmetry (found in most other animals). Some animals, like sponges, are asymmetrical.

Significance of the Animal Kingdom

The animal kingdom has a great diversity of species, which contributes to maintaining the ecological balance of life on Earth. It is also important to ensure that all the biological processes are functioning effectively. Some of the major points regarding the significance of the animal kingdom are discussed below:

  • Animals in the animal kingdom are integral parts of the ecosystem and have their roles, such as herbivores, carnivores and omnivores, which regulate the entire population dynamics.

  • Maintains the energy flow between all the ecosystems.

  • Biodiversity within the animal kingdom is also responsible for several ecological processes, such as nutrient cycling, decomposition and habitat formation.

  • Many animals, such as birds, insects and mammals, are also part of the very important process of pollination and seed dispersal.

  • Decomposers are also part of the animal kingdom, which play an important role in decomposition and nutrient recycling back into the soil.

Also Read:

CoelomClass Chondrichthyes
Digestive System of Earthworms
Reproductive System of the Earthworm
VermicompostingOsteichthyes

Recommended Video On Animal Kingdom Subphylum


Frequently Asked Questions (FAQs)

Q: How do animals influence the evolution of plants?
A:
Animals influence plant evolution through various interactions including herbivory, pollination, and seed dispersal. These interactions can drive the development of plant defenses, attractive features for pollinators, or seed structures that facilitate animal dispersal. This co-evolution between plants and animals has been a major force in shaping terrestrial ecosystems.
Q: What is the role of animal cognition in survival and adaptation?
A:
Animal cognition, including learning, memory, problem-solving, and decision-making, plays a crucial role in survival and adaptation. It allows animals to flexibly respond to environmental challenges, learn from experiences, and in some cases, use tools or develop complex social strategies. The level of cognitive ability varies widely among animal groups.
Q: How do animals cope with competition for resources?
A:
Animals cope with competition for resources through various strategies including niche partitioning (using different parts of the habitat or different food sources), territorial behavior, developing specialized adaptations, altering activity patterns, or migrating to new areas. Competition is a major driving force in evolution and shapes animal communities.
Q: What is the significance of animal biomechanics?
A:
Animal biomechanics, the study of how animals move and function mechanically, is crucial for understanding animal behavior, evolution, and adaptation. It explains how animals achieve efficient movement in different environments, how body structures support various functions, and can inspire technological innovations in fields like robotics and materials science.
Q: What is the role of animal vocalizations?
A:
Animal vocalizations serve multiple purposes including attracting mates, defending territories, warning of predators, maintaining social bonds, and expressing emotional states. The complexity and variety of vocalizations can reflect the social structure and cognitive abilities of a species.
Q: How do animals contribute to seed dispersal?
A:
Animals contribute to seed dispersal through various mechanisms including eating fruits and excreting seeds (endozoochory), carrying seeds on their fur or feathers (epizoochory), or actively collecting and storing seeds (like squirrels). This process is crucial for plant reproduction and maintaining biodiversity in ecosystems.
Q: What is the concept of convergent evolution in animals?
A:
Convergent evolution occurs when unrelated or distantly related animals develop similar traits independently in response to similar environmental pressures. This results in analogous structures or behaviors that serve similar functions but have different evolutionary origins, such as the wings of birds, bats, and insects.
Q: How do animals interact with microorganisms?
A:
Animals interact with microorganisms in various ways, including symbiotic relationships (like gut bacteria aiding digestion), parasitic infections, and immune responses to pathogens. These interactions can significantly influence an animal's health, behavior, and evolution. Some animals even cultivate beneficial microorganisms, like leaf-cutter ants growing fungus for food.
Q: What is the importance of animal dispersal in ecosystems?
A:
Animal dispersal, the movement of individuals from their birth site to breeding sites, is crucial for maintaining genetic diversity within populations, colonizing new habitats, and responding to environmental changes. It also plays a key role in seed dispersal for many plant species, influencing ecosystem structure and function.
Q: How do animals maintain genetic diversity?
A:
Animals maintain genetic diversity through sexual reproduction, which combines genetic material from two parents. Mechanisms like random mating, genetic recombination during meiosis, and mutations contribute to genetic variation. Some species also have specific behaviors that promote outbreeding and avoid inbreeding.
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