ANSWER is jointed legs.Arthropoda - The word ‘arthropod’ means ‘jointed legs’.Ex: houseflies, spiders, scorpions, prawns, butterflies and crabs.The Hierarchy of Classification of living organisms - Living organisms are classified into five kingdoms, by Whittaker, i.e. Kingdom MONERA,Kingdom Protista,Kingdom Fungi,Kingdom Plantae,Kingdom Animalia.Further classification is done by the following scheme: Kingdom, Phylum (for animals) / DIVISION (for plants), Class, ORDER, Family, Genus, Species.Kingdom Animalia is further classified based on the extent and type of the body design differentiation found, as below: