Class Mammalia Linnaeus, 1758 - mammals
   Subclass Theria Parker & Haswell, 1897
     Order Carnivora Bowdich, 1821 - carnivores
       Suborder Caniformia Kretzoi, 1943
         Family Phocidae Gray, 1821 - true seals
           Genus Halichoerus Nilsson, 1820 [monotypic] - gray seal
             1 Halichoerus grypus (Fabricius, 1791) - gray seal