are more closely related to the hexapods than they are to any other crustaceans (oligostracans and multicrustaceans).

The 67,000 described species range in size from Stygotantulus stocki at 0.1 mm 3 abbr=on, to the Japanese spider crab with a leg span of up to 3.8 m and a mass of 20 kg. Like other arthropods, crustaceans have an exoskeleton,