Which is the largest group in the animal kingdom?

Which is the largest group in the animal kingdom?

• A. Mollusks
• B. Arthropods
• C. Vertebrates
• D. Nematodes

Answer: (B)

Arthropods are the largest group by species count. This vast phylum includes insects, arachnids, crustaceans, and myriapods, and their success comes from features like an exoskeleton that provides protection and support, segmented bodies, and jointed limbs that enable a wide range of movements. Insects alone account for a huge share of described animal species, driving the overall diversity of arthropods far beyond the other groups listed. Mollusks are numerous in some contexts but have far fewer described species than arthropods. Vertebrates comprise only a small fraction of animal diversity, and nematodes, while extremely abundant in numbers, do not reach the same level of species diversity as arthropods.

Arthropods are the largest group by species count. This vast phylum includes insects, arachnids, crustaceans, and myriapods, and their success comes from features like an exoskeleton that provides protection and support, segmented bodies, and jointed limbs that enable a wide range of movements. Insects alone account for a huge share of described animal species, driving the overall diversity of arthropods far beyond the other groups listed. Mollusks are numerous in some contexts but have far fewer described species than arthropods. Vertebrates comprise only a small fraction of animal diversity, and nematodes, while extremely abundant in numbers, do not reach the same level of species diversity as arthropods.