3 subphyla, 8 classes, 26 orders, more than 200 families, more than 1700 genera, thousands of species......the classification of the Brachiopoda is complicated.

Still during the 19th century, authors as famous as Cuvier, Lamarck, Linné, Menke... seemed persuaded that the brachiopods did not form a distinct evolutionary branch. They generally classified them among the Lamellibranchia (Mollusca Bivalvia). It is Hancock who, for the first time, brought closer the brachiopods to the Bryozoa and suggested including them in the subphylum Molluscoides, created by Milne-Edwards. Other authors tended to gather them with the Polychaete worms. However, in older schemes, classification have always relied extensively on the morphology of the fossil shells.

New analysis, including genetic studies of living species, makes the taxonomy change. Nowadays, Brachiopoda, together with Phoronida and Bryozoa, constitute de superphylum Lophophorata.

At all events, even today, taxonomy is still unstable and opinions are divided on certain methods of classification.

Systematic (taxonomy) : science of classification of living creatures.

Polychaete worm : marine segmented worm