(a) : Spiny anteater (Echidna) is a prototherian mammal whereas, sea urchins and sea cucumber are echinoderms. Silver fish (Lepisma) is an insect, Cuttle fish (Sepia) is a mollusc and flying fish (Exocoetus) is a bony fish. Centipede is class chilopoda, Millipede is class diplopoda and Scorpion and Spider are class arachnida of Phylum Arthropoda.