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 familyPhocidæthe eared seals, orOtariidæ, 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 (Odobænidæ). 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 thePhocidæregularly 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 ofthe water by a strong and sudden movement of the hind-limbs. When once on land, they may remain there for days and even weeks together, till compelled by hunger to return to the sea.
seal
The senses of the seal are highly developed. The eye, for instance, is full and globular, and thus specially adapted to catch every ray of light when the animal is in the water. It is noteworthy that seals can shed tears under the influence of excitement, and especially when in pain. And the idea of the ancients that these animals are attracted by music and singing appears to be founded on fact.
Their usual cry is a sharp bark, but when angered they give vent to dog-like snarlings. Seals always associate in parties, which may comprise hundreds of individuals. The young, which are beautiful little creatures, are tenderly and affectionately nurtured by their parents, who protect them from danger by every means in their power.
Young seals have a coat quite different from that of the adult; this baby coat in the case of the second British species, the grey seal (Halichærus grypus), being wholly white. In colour, the common seal varies greatly, the coat being sometimes yellowish and sometimes light grey with blackish mottlings and marblings. The so-called grey seal is generally much darker in colour, but is best distinguished from the common species by its greatly superior size and its relatively larger and blunter teeth.
All seals are polygamous, which leads to fights among the males for the possession of the females; but in other respects they are gentle and affectionate, easily tamed if taken young, and displaying great capacity for education. As a rule, only a single cub is produced at a birth, but there may be twins.