One of the mysteries of the English language finally explained.
Definition of Articulata in English:
Articulata
noun
ZoologyTreated as plural. A major group of animals comprising invertebrates with bilateral symmetry and an external skeleton, having the body and limbs composed of segments jointed together, comprising principally annelids (segmented worms) and arthropods; (also articulata) animals of this group collectively.
Origin
Early 19th century; earliest use found in Annals of Philosophy. From scientific Latin Articulata, neuter plural of classical Latin articulātus.