the root (no rank)
Eukaryota (domain)
Metazoa (kingdom)
Echinodermata (phylum)
Echinozoa (superclass)
Echinoidea (class)
Euechinoidea (subclass)
Arbacoida (order)
[hide inferior taxa]
Arbacia lixula (species)
Arbacia punctulata (species)