Wilson has pointed out in his article upon seals in the Discovery Report[62] that the Weddell and the crab-eater seal, which are the two commoner of the Antarctic seals, have agreed to differ both in habit and in diet, and therefore they share the field successfully. He shows that "the two penguins which share the same area have differentiated in a somewhat similar manner." The Weddell seal and the Emperor penguin "have the following points in common, namely, a littoral distribution, a fish diet and residential non-migratory habit, remaining as far south the whole year round as open water will allow; whereas the other two (the crab-eating seal and the Adélie penguin) have in common a more pelagic habit, a crustacean diet, and a distribution definitely migratory in the case of the penguin, and although not so definitely migratory in the case of the seal, yet checked from coming so far south as Weddell's seal in winter by a strong tendency to keep in touch with pelagic ice."[63] Wilson considers that the advantage lies in each case with the "non-migratory and more southern species," i.e. the Weddell seal and the Emperor penguin. I doubt whether he would confirm this now. The Emperor penguin, weighing six stones and more, seems to me to have a very much harder fight for life than the little Adélie.
Before the Discovery started from England in 1901 an 'Antarctic Manual' was produced by the Royal Geographical Society, giving a summary of the information which existed up to that date about this part of the world. It is interesting reading, and to the Antarctic student it proves how little was known in some branches of science at that date, and what strides were made during the next few years. To read what was known of the birds and beasts of the Antarctic and then to read Wilson's Zoological Report of the Discovery Expedition is an education in what one man can still do in an out-of-the-way part of the world to elucidate the problems which await him.
The teeth of a crab-eating seal "are surmounted by perhaps the most complicated arrangement of cusps found in any living mammal."[64] The mouth is so arranged that the teeth of the upper jaw fit into those of the lower, and "the cusps form a perfect sieve ... a hitherto unparalleled function for the teeth of a mammal."[65] The food of this seal consists mainly of Euphausiae, animals much like shrimps, which it doubtless keeps in its mouth while it expels the water through its teeth, like those whales which sift their food through their baleen plates." This development of cusps in the teeth of the [crab-eating seal] is probably a more perfect adaptation to this purpose than in any other mammal, and has been produced at the cost of all usefulness in the teeth as grinders. The grit, however, which forms a fairly constant part of the contents of the stomach and intestines, serves, no doubt, to grind up the shells of the crustaceans, and in this way the necessity for grinders is completely obviated."[66]
The sea-leopard has a very formidable set of teeth suitable for his carnivorous diet. The Weddell, living on fish, has a more simple group, but these are liable to become very worn in old age, due to his habit of gnawing out holes in the ice for himself, so graphically displayed on Ponting's cinematograph. When he feels death approaching, the crab-eating seal, never inclined to live in the company of more than a few of his kind, becomes still more solitary. The Weddell seal will travel far up the glaciers of South Victoria Land, and there we have found them lying dead. But the crab-eating seal will wander even farther. He leaves the pack. "Thirty miles from the sea-shore and 3000 feet above sea-level, their carcases were found on quite a number of occasions, and it is hard to account for such vagaries on other grounds than that a sick animal will go any distance to get away from its companions"[67] (and perhaps it should be added from its enemies).
Often the under sides of the floes were coloured a peculiar yellow. This coloration is caused by minute unicellular plants called diatoms. The floating life of the Antarctic is most dense. "Diatoms were so abundant in parts of the Ross Sea, that a large plankton net (18 meshes to an inch) became choked in a few minutes with them and other members of the Phytoplankton. It is extremely probable that in such localities whales feed upon the plants as well as the animals of the plankton."[68] I do not know to what extent these open waters are frequented by whales during the winter, but in the summer months they are full of them, right down to the fringe of the continent. Most common of all is the kind of sea-wolf known as the Killer Whale, who measures 30 feet long. He hunts in packs up to at least a hundred strong, and as we now know, he does not confine his attacks to seal and other whales, but will also hunt man, though perhaps he mistakes him for a seal. This whale is a toothed beast and a flesh-eater, and is more properly a dolphin. But it seems that there are at least five or six other kinds of whales, some of which do not penetrate south of the pack, while others cruise in large numbers right up to the edge of the fast ice. They feed upon the minute surface life of these seas, and large numbers of them were seen not only by the Terra Nova on her various cruises, but also by the shore parties in the waters of McMurdo Sound. In both Wilson and Lillie we had skilled whale observers, and their work has gone far to elucidate the still obscure questions of whale distribution in the South.
The pack-ice offers excellent opportunities for the identification of whales, because their movements are more restricted than in the open ocean. In order to identify, the observer generally has only the blow, and then the shape of the back and fin as the whale goes down, to guide him. In the pack he sometimes gets more, as in the case of Balaenoptera acutorostrata (Piked whale) on March 3, 1911. The ship "was ploughing her way through thick pack-ice, in which the water was freezing between the floes, so that the only open spaces for miles around were those made by the slow movement of the ship. We saw several of these whales during the day, making use of the holes in the ice near the ship for the purpose of blowing. There was scarcely room between the floes for the whales to come up to blow in their usual manner, which consists in rising almost horizontally, and breaking the surface of the water with their backs. On this occasion they pushed their snouts obliquely out of the water, nearly as far as the eye, and after blowing, withdrew them below the water again. Commander Pennell noted that several times one rested its head on a floe not twenty feet from the ship, with its nostrils just on the water-line; raising itself a few inches, it would blow and then subside again for a few minutes to its original position with its snout resting on the floe. They took no notice of pieces of coal which were thrown at them by the men on board the ship."[69]
But no whale which we saw in the pack, and we often saw it elsewhere also, was so imposing as the great Blue whale, some of which were possibly more than 100 feet long. "We used to watch this huge whale come to the surface again and again to blow, at intervals of thirty to forty seconds, and from the fact that at each of four or five appearances no vestige of a dorsal fin was visible, we began to wonder whether we had not found the Right whale that was once reported to be so abundant in Ross Sea. Again and again the spout went up into the cold air, a white twelve-foot column of condensed moisture, followed by a smooth broad back, and yet no fin. For some time we remained uncertain as to its identity, till at last in sounding for a longer disappearance and a greater depth than usual, the hinder third of the enormous beast appeared above the surface for the first time with its little angular dorsal fin, at once dispelling any doubts we might have had."[70]
It is supposed to be the largest mammal that has ever existed.[71] As it comes up to blow, "one sees first a small dark hump appear and then immediately a jet of grey fog squirted upwards fifteen to eighteen feet, gradually spreading as it rises vertically into the frosty air. I have been nearly in these blows once or twice and had the moisture in my face with a sickening smell of shrimpy oil. Then the hump elongates and up rolls an immense blue-grey or blackish-grey round back with a faint ridge along the top, on which presently appears a small hook-like dorsal fin, and then the whole sinks and disappears."[72]
To the biologist the pack is of absorbing interest. If you want to see life, naked and unashamed, study the struggles of this ice-world, from the diatom in the ice-floe to the big killer whale; each stage essential to the life of the stage above, and living on the stage below:
THE PROTOPLASMIC CYCLE