Phylum Arthropoda: “jointed feet” External features of arthropods Subphylum Chelicerata Class Xiphosura: horseshoe crabs Class Arachnida: Order Scorpiones Order Pseudoscorpiones Order Uropygi: whipscorpions Order Opiliones: daddy longlegs Order Acari: mites Order Araneae: spiders A spider that eats other spiders . . . jumping spider <i>Portia</i> Subphylum Mandibulata Crustacea: Order Decapoda: shrimp, crayfish, lobsters, crabs Decapod parts Order Isopoda: pillbugs, sowbugs Class Diplopoda: millipedes Class Chilopoda: centipedes Class Insecta Photo sources