--- EUROPE IN THE AGE OF ICE

CHAPTER XI. HOW THE BACKBONED ANIMALS HAVE RETURNED TO THE WATER, AND LARGE MILK-GIVERS IMITATE THE FISH.

“On revient toujours à ses premiers amours,” says the French song. But who would have thought that, after rising step by step above the fish, and tracing the history of the backboned animals through

their development in the air and over the land, till we brought them to a stage of intelligence second only to man, we should have to follow them back again to the water and find the highly gifted milk-givers taking on the form and appearance of fishes? Nevertheless it is so, for seals and whales are as truly flesh-eating milk-givers as bears and wolves; nor are they much behind them in intelligence, for we all know how teachable and affectionate seals and sea-lions are, while what little is known of the life of whales shows that they are devoted mothers, and their well convoluted though small brains are a proof that they are by no means wanting in intelligence.

Yet the whales and dolphins, at any rate, have not only adopted a sea life, but have limbs so like a fish’s fins that we can scarcely call them by any other name, and they are so completely water animals that they cannot even return to the land.

Now we should be quite puzzled to account for such curious forms as these warm-blooded animals, half transformed into fish, if it were not that we know of several land animals belonging to different groups which have gone part of the way towards a fish life. Thus among the reptiles we have the oceanic turtles and the sea snakes; among birds the penguins, whose wings have almost become fins. Then among the milk-givers we have the web-footed Duck-billed Platypus, the Yapock or web-footed opossum of South America, the Desman and the Beaver, the Polar Bear, and last but not least the Otters, web-footed animals nearly allied to the weasels, which seek their food entirely in the water.

The common Otter of Europe and America though he moves quickly and actively on land, has webbed toes with only short claws standing out beyond the swimming foot, and he spends the greater part of his life in the river, making his home in a hollow of the bank beneath the overhanging roots of trees. There he may still be seen in many of our English rivers, his soft brown fur shining as he swims along, diving under water for a fish, which he brings out on to the bank to eat, holding it in his fore paws.

But there is an otter which has deserted the old land life much more completely than this, for the great Sea-Otters of the North Pacific, about four or five feet long (see Fig. 79), never care even to come on shore, but, when they have dived for their prey, turn on their backs and float while they eat it, holding the sea-urchins, crabs, or fish, in their front paws. They even nurse their young ones in the same fashion, dandling them in their arms as they lie face upwards on the sea; and they rear them entirely on the thick beds of kelp off the coasts of the North Pacific Ocean, never bringing them on land.

These sea-otters may be seen in hundreds off the coasts of Alaska and California, basking on the wet rocks, playing, leaping, and plunging in the water, till some alarm makes each mother seize her little one in her teeth and dive under in an instant.

They are twice the size of the River Otter, and in many points more like seals, for though their front paws are short and cat-like, their hind feet are flat flippers, with a long outer toe; their face too is broad and short, and their teeth are neither cutting like the weasels nor flattened like the bears, but covered with rounded knobs, well fitted for crushing crab-shells and the bones of the fish on which they feed.

Fig. 79.

Sea-Otter.[180]—(From Wolf.)

Showing the front paws, and the hind webbed feet.

We see, then, that it is quite possible for land-animals to have near relations specially adapted for a sea life. But the otter is still distinctly a four-footed creature, with free arms and legs, and we can trace his connection with the weasel tribe. It is quite different with the three groups of real fin-footed animals—the Seals and Walruses, the Manatees, and the Whales. Though we can trace their likeness bone by bone to the land animals, yet they have become so different as to show that they must have branched off long long ago; so long indeed that we cannot even guess at the

Footnote 180. Enhydra marina.

relations of the whales, while the seals have only a distant resemblance to the bear family, and the sea-cows or manatees to the ancestors of the hoofed animals and elephants. Nor shall we wonder to find the whales so much the most fitted for the sea, when we learn that they were already living in the water when we first meet with the great army of milk-givers (see p. 211) just after the Chalk Period, so that they have probably had a much longer spell of watery life than the seals and sea-cows, whose remains we only find later.

Yet even the seals are so much altered from anything we see on land, that few people would believe at first sight that they have the same skeleton as a bear. We need not leave the British shores to study these pretty creatures, for they still come to the coasts of Wales, Cornwall, and Ireland; while in the Hebrides they may be seen lying fast asleep on the rocks at low tide out at sea, one, placed higher than the rest, keeping awake as sentinel to give warning at the least approach of danger.

But if we begin our study with the common seal we shall be much puzzled, for he is very unlike a land animal. His round neckless body tapering away to the tail, where the hind flippers stretch out behind like fish’s fins, reminds us far more of a tunny fish than of a four-footed milk-giver; while the front flippers, coming out so finlike from his side, give us very little idea of legs (see Fig. 81). No! in order to compare these fin-footed[181] creatures with land animals we shall do far better to travel up to the Aleutian Islands at the entrance of Behring’s

Footnote 181. Pinnipedia.

Straits, and visit the Fur Seals and Sea Lions, from which we get our seal-skins, and the Walruses which sometimes lie there sleeping on the rocks, though their real home is farther north within the Arctic Circle, round the coasts of Nova Zembla, Spitzbergen, and Greenland.

Fig. 80.

Skeleton of a Sea Lion.

Showing how the whole foot rests on the ground, as in the Bear Family.

th, thigh; l, leg; h, heel; f, foot; a, upper-arm; fa, fore arm; ha, hand.

These creatures, although they have “flippers,” and are truly fin-footed, are much more like land animals than the smaller seals, for they plant their whole foot on the ground as a bear does, and walk, or, more properly, “flop along” on all fours. A mere glance at the skeleton of the sea lion, which is one of these higher kind of seals with a slight outer

ear,[182] shows that it is a four-footed animal, with five toes to each foot, the great toes and the thumbs being the largest. We can see distinctly the short thighs and the long shanks, which give the hind flippers their lanky appearance, and we see, too, the broad stumpy arms, which give such strength to the front flippers in swimming. For the eared seals and walruses use their fore flippers very much in the water, while the true seals swim almost entirely with the hind flippers, and use the front ones chiefly for guiding themselves.

And now if we turn to the living fur seal we find that the reasons are twofold which make us forget that his limbs are legs. In the first place, the skin of his body comes down very low over his arms (see Fig. 81), while the hand is encased in skin, with only mere traces of nails upon it Then as regards his hind legs, not only are the feet made into flippers, in which the toes are joined by a loose flexible skin, so that they can move them freely when swimming, but the legs themselves are strapped back by a skin passing right across his tail, so that his thighs are kept flat against his side, and only the lower part of the legs has power to move. We lose sight, then, of the limbs, and see very little more than the feet, which are disguised by being turned into flippers.

Now if we once think what is the object of a seal’s life, this curious change in its body is at once explained. For seals are the hunters of the sea; fish-food is to them what flesh-food is to lions, wolves, and bears, only that they have a much wider field to hunt in, for they have the whole ocean

Footnote 182. Otariidæ (ous, otos, an ear), eared Seals.

for their feeding ground, and no one to dispute it with them but the sea-otter in places near the land, and the porpoises and other fish-feeding whales out at sea. In consequence of this we find seals of some kind in almost all parts of the world, except the Indian Ocean, though they evidently prefer the cooler regions. Even the large sea lions live in the North Pacific, as far up as the Aleutian Isles, and in the South Pacific down to the Falkland Islands and Kerguelen’s Land, and play about the shores of the Cape, New Zealand, and Australia.

Fig. 81.

A Fur Seal,[183] one of the Sea Lions; and a common Seal.[184]

Showing how the Sea Lion walks on the flat hind feet, while the seal’s flippers lie back in a line with the body; note also the absence of an external ear in the seal.

They have evidently been very successful in exchanging flesh-feeding for fish-feeding, and if we consider for a moment what changes a four-footed land animal would wish to make in its body in order

Footnote 183. Callorhinus (Otaria) ursinus.

Footnote 184. Phoca vitulina.

to swim and dive in the water, we shall see that these changes have taken place in the seals.

First, a flexible body is required to wind and twist rapidly in the water, and this the seal arrives at by having the cushions of gristle between its joints very large and thick, while even its ribs are joined to its back by gristly rods, making its whole body very lissom. Next, a small head, offering little resistance to the water is an advantage, and this we find in all seals, while the short neck and extremely sloping narrow shoulders well encased in fat, make the body slope away gently with no jutting angles, but a round smooth surface from head to tail where it narrows like the tail of a fish. The next step is to do away with long angular arms and legs, which would impede it in diving and swimming, and here the seal meets the difficulty, not by losing its leg and arm bones, but by having them so shortened and encased in the skin that only the useful broad flippers are free, while the hind legs are set upon a very narrow hip joint (see Fig. 80), so that they bend backwards and work close to the body. Lastly, such a warm-blooded animal would want clothing to prevent it from being chilled in icy cold water, and here we find two protections. First, under the skin is a layer of oily fat, which, while it reminds us of the fat accumulated by bears before they settle down to their winter’s sleep, has become in the seals a dense oily mass, acting like a thick blanket in keeping up the warmth of the body; and secondly, the seal, like its distant relations the bears, has a dense furry covering, and over this a number of coarse long hairs, which give it that shining oily look we notice in all seals. No doubt every one has wondered, when watching seals in zoological gardens, where the fur can be which makes our sealskin muffs and jackets. The fact is, that this under fur is quite out of sight in the living seal, being covered by the coarse hairs; but if we could turn these aside, even in common seals, we should see the soft undergrowth beneath, and in the fur seals it is much thicker. Now the roots of these coarse hairs are deeper in the flesh than the roots of the soft undergrowth, and when the uppermost layer of the skin on which the fur grows is sliced off, the coarse hairs are cut away from their deep roots below, and can then be pulled out, leaving only the fur behind.

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