Spiders are not insects, but are arthropods, animals with hard exoskeletons and segmented bodies, and in the same phylum that includes insects. Phylum arthropoda includes the classes crustacea (such as lobsters and crabs), chilopoda (centipedes), diplopoda (millipedes), insecta, and arachnida (spiders and other archanids). (As a reminder, in Linnaean scientific classification of binomial nomenclature, the seven main divisions, from largest to smallest, are Kingdom, Phylum, Class, Order, Family, Genus, and Species.)