Arthropods include millions of species that are alive today: insects, arachnids or spiders and scorpions, millipedes or dtplopodans, centipedes or chilopodans, and crabs, shrimps and other crustaceans.
These are covered in the following pages, starting with the long-extinct trilobites.
The uniting feature of arthropods is their hard outer casing and usually numerous jointed limbs.
The name means 'joint-foot'.