earless seal vs hair seal

earless seal

noun
  • Any of the seals in the taxonomic family Phocidae characterized by lacking external ear flaps; true seals. 

hair seal

noun
  • especially the true seals or earless seals of family Phocidae. 

  • Any of various seals which have coarse hair rather than fur 

How often have the words earless seal and hair seal occurred in a corpus of books? (source: Google Ngram Viewer )