Which phylum accounts for 85% of all animal species?

• A. Chordata
• B. Arthropoda
• C. Mollusca
• D. Echinodermata

Answer: (B)

The phylum that accounts for approximately 85% of all animal species is Arthropoda. This vast group includes organisms such as insects, arachnids (spiders and scorpions), myriapods (centipedes and millipedes), and crustaceans (crabs, lobsters, and shrimp). The remarkable diversity within Arthropoda can be attributed to several factors, including their adaptable exoskeleton, segmented bodies, jointed appendages, and varied modes of reproduction and development. These features have allowed arthropods to occupy diverse ecological niches across terrestrial, marine, and freshwater environments, resulting in their status as the largest phylum in the animal kingdom. This incredible variety and adaptability are key reasons why they represent a significant majority of the animal species on Earth.