General description

The term phylum was coined in 1866 by Ernst Haeckel from the Greek (, 'race, stock'), related to (, 'tribe, clan'). Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as a group ("a self-contained unity"): "perhaps such a real and completely self-contained unity is the aggregate of all species which have gradually evolved from one and the same common