Which is the largest Phylum in the Animal Kingdom?

Answer

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Hint: Jointed appendages allow more movement, protecting them from predators, leading to their success.

Complete answer:
Arthropoda is the largest Phylum in the Animal Kingdom. Over two-thirds of all named species on earth are Arthropods. They consist of over 90,000 species.

Additional Information:
They have an organ-system level of organization. Bilaterally symmetrical, triploblastic, segmented, coelomate, diaceous, oviparous are a few characteristics of this phylum. They have a chitinous exoskeleton, which is another reason which led to their success. The body can be distinctly divided into head, thorax, and abdomen. Respiratory organs are gills, book gills, book lungs, or tracheal systems. They have an open circulatory system and excretion takes place through malpighian tubules. They undergo internal fertilization. Sensory organs, like antenna, eyes, and balance organs are present.
Arthropods are traditionally divided into 5 subphyla: Trilobitomorpha (Trilobites), Chelicerata, Crustacea, Myriapoda, and Hexapoda; which are further divided into classes. Arthropods are important in maintaining the ecological balance in nature and provide natural services to humans and act as the pollinators, natural enemies, scavengers, leaf-litter sweepers, garbage collectors, soil conditioners and natural fertilizer producers in nature.

Notes:
-Limulus (King Crab) is known as the living fossil.
-Mollusca is the second largest Phylum while Chordata is the third-largest Phylum.
-The term ‘arthros’ means joint and ‘podas’ means appendages, hence the name, due to the presence of jointed appendages.