Test: Classification of Animal Kingdom - SSC CGL MCQ

The basis of classification of the animal kingdom is primarily determined by the mode of nutrition. Animals are classified based on their heterotrophic mode of nutrition, which means they cannot produce their own food and rely on external sources for nutrition.

Bilateral Symmetry enables organisms to be divided into two identical left and right halves through only one plane. This type of symmetry is commonly found in Annelids, Arthropods, Molluscs, and other organisms, where the body can be mirrored along a single plane. This symmetry is advantageous for animals that exhibit directional movement, as it helps in streamlining their body structure for efficient locomotion.

Organisms in the Phylum Porifera exhibit asymmetrical symmetry. This means that they cannot be divided into two equal halves through a median plane. Sponges, which belong to the Phylum Porifera, are a classic example of organisms with asymmetrical body symmetry. This unique characteristic sets them apart from organisms with radial, bilateral, or spherical symmetry, making asymmetrical symmetry a defining feature of Porifera.

Sponges are characterized by their mostly asymmetrical shape and primitive cellular organization, existing at a cellular level of organization. This unique feature distinguishes them from more complex organisms. The cellular structure of sponges allows for functions such as food gathering, respiratory exchange, and waste removal to take place efficiently within their bodies.

Cnidarians are characterized by their radially symmetrical body structure. They can either be sessile, meaning they attach themselves to a surface, or free-swimming. This feature distinguishes them from organisms with bilateral symmetry, like humans and other vertebrates. The sessile nature of cnidarians plays a crucial role in their ecological interactions within marine environments, where they can anchor themselves securely for feeding and protection.

Roundworms from the phylum Aschelminthes possess a pseudocoelomate body plan. This characteristic indicates that their body cavity is not fully lined by mesoderm, unlike true coelomates, but rather partially lined. The presence of a pseudocoelom offers structural support to internal organs and provides a space for various physiological functions. This distinction sets roundworms apart from other organisms within the phylum and contributes to their unique biological characteristics and adaptations.

Echinodermata is the phylum that possesses a water vascular system as a distinctive feature. This system is essential for various functions such as locomotion, feeding, and respiration in echinoderms. It is a hydraulic system that aids in movement, food capture, and gas exchange, showcasing a unique adaptation in these marine animals.

Reptiles are known for their characteristic way of movement - they move in a creeping or crawling manner. This adaptation suits their primarily terrestrial lifestyle, aiding in their survival and hunting strategies.

Class Aves, or birds, are known for having a fully four-chambered heart, which distinguishes them from reptiles and most other animals. This adaptation is crucial for the high metabolic demands of birds due to their ability to fly. The presence of a four-chambered heart allows for efficient circulation and oxygenation, supporting their active lifestyle in the air.

The organ level of organization in terms of body symmetry is exemplified by animals where tissues are grouped to form organs. In this level of organization, each organ is specialized for a particular function, showcasing a higher degree of complexity and specialization in the body structure.

Radial Symmetry is the type of symmetry that allows organisms to be divided into two identical halves through any plane passing through the central axis. Organisms such as Coelenterates, ctenophores, and echinoderms exhibit radial symmetry, where their body parts are arranged around a central point like spokes on a wheel. This type of symmetry is beneficial for organisms that require equal access to resources from all directions, aiding in their survival and adaptation to their environments.

The phylum Chordata is known for possessing a notochord during embryonic development. The notochord is a rod-like structure that develops on the dorsal side of animals within this phylum. This structure is essential in providing support and aiding in locomotion. Animals belonging to the phylum Chordata include a wide range of familiar creatures such as vertebrates, making the notochord a crucial characteristic in the early development of these organisms.

The term "Coelenterata" is derived from the Greek word "kilos," which translates to "hollow-bellied." This term signifies a defining characteristic of this phylum, referring to the central cavity or gastrovascular cavity present in many of the organisms classified under this group. The hollow-bellied nature of Coelenterates plays a significant role in their feeding and digestion processes.

Flatworms from the phylum Platyhelminthes exhibit a triploblastic body organization, meaning they have three germ layers: the ectoderm, mesoderm, and endoderm. This characteristic is essential for their structural development and differentiation of tissues, setting them apart from organisms with simpler body plans. Triploblastic organization enables flatworms to perform more complex physiological functions and exhibit a higher level of anatomical complexity compared to simpler organisms with only two germ layers.

Arthropods are characterized by their bilateral symmetry, which is a fundamental feature that sets them apart from other phyla in the animal kingdom. This symmetrical arrangement means that the body can be divided into two mirror-image halves along a central axis, showcasing a balanced and organized structure in these organisms.