Cheliceramorpha
Arachnida
(Arachnids)
Acarii
(Mites and ticks)
Amblypygi
Araneae
(Spiders)
Opiliones (Harvestmen)
Palpigradi
Pseudoscorpiones
Ricinuclei
Schizomida
Scorpiones
(Scorpions)
Solifugae
Thelyphonida
Trigonotarbida
Eurypterida
(Sea scorpions)
Xiphosura
(Horseshoe crabs)