THE SEAL 



(Phoca vitulina) 



OF all mammals except whales, dolphins, and sea-cows, the true seals, of 

 which the common British species is the typical representative, are those 

 which have become most completely adapted to an aquatic existence. This 

 is shown by the spindle-shaped form of the body, the total absence of external ears, 

 the conversion of the fore-limbs into flippers, and the backward direction of the 

 hind pair, which are also flipper-like, and lie parallel to the short tail to form an 

 efficient rudder-like organ. 



Seals are evidently descended from land Carnivora, and possibly from that 

 long extinct group the Creodontia. When fully developed, their cheek-teeth 

 consist of a single middle cusp, flanked by a smaller one in front and behind ; and 

 there are no teeth specially corresponding with the scissor-like pair characteristic 

 of the modern land Carnivora. This fact, unless the teeth are degenerate, is all in 

 favour of the direct descent of seals from creodonts. 



From the true seals of the family Phocidce the eared seals, or Otariidce, 

 differ by retaining small external ears, as well as by the fact that the hind-flippers 

 are not permanently turned backwards ; this latter feature being also distinctive of 

 the walrus (Odobcenidce). In addition to being the most specialised of the aquatic 

 Carnivora, the true seals are also the most widely distributed, inhabiting nearly all 

 seas, and being likewise found in the Caspian Sea and in Lakes Aral and Baikal. 

 Although seals go on land nightly to sleep, and likewise spend a considerable 

 amount of time in the day on the shore or on ice, while the females give birth to 

 their young on land, none of the Phocidce regularly leave the water for a period of 

 several weeks during the breeding-season, after the fashion of their eared cousins. 

 Neither do any of them yield commercial sealskin, which is a product of certain 

 members of the eared groups. Commercially, they are therefore valued only for 

 their hides and oil, for the sake of which vast numbers are annually slaughtered. 



Seals are adepts in swimming and diving, and have the power of closing 

 their nostrils and the apertures of their ears while under water, although they 

 are unable to remain beneath the surface for anything like so long as whales and 

 dolphins. The food of the common seal, as well as most other kinds, consists 

 chiefly of fishes, for capturing and holding which their sharply cusped teeth are 

 admirably adapted. Graceful and active as are their movements in water, on land 

 they are comparatively awkward and ungainly; progression being effected by 

 means of the limbs, accompanied by sudden flexures of the body, so that it in some 

 degree partakes of the nature of hopping. To land, seals shoot themselves out of 



