The Collaborative International Dictionary of English v.0.48:

Sawtooth \Saw"tooth`\, n. (Zool.)
   An arctic seal (Lobodon carcinophaga), having the molars
   serrated; -- called also crab-eating seal.
   [1913 Webster]

WordNet (r) 3.0 (2006):

crab-eating seal
    n 1: silvery grey Antarctic seal subsisting on crustaceans [syn:
         crabeater seal, crab-eating seal]