Although anatomists have good reason for suspecting that all the members of the Whale Tribe are directly descended from river-dwelling forms, if not indeed, more remotely, from some land animal, there is something appropriate in the fact of the vast ocean, which covers something like three-quarters of the earth's surface, producing the mightiest creatures which have ever lived. There should also be some little satisfaction for ourselves in the thought that, their fish-like form notwithstanding, these enormous beings really belong to the highest, or mammalian, class of animal life.
One striking feature all these many-sized cetaceans have in common, and that is their similarity of form. Though they may vary in length from 70 to 7 feet, their outline shows a remarkable uniformity. Important internal and even external differences there may be. A whale may be toothed or toothless; a dolphin may be beaked or round-headed; either may be with or without a slight ridge on the back or a distinct dorsal fin; but no cetacean could well be mistaken for an animal of any other order. It is as well to appreciate as clearly as possible this close general resemblance between the largest whale and the smallest dolphin, as the similarity is one of some interest; and we may estimate it at its proper worth if we bear in mind that two species of cetaceans, outwardly alike, may not, perhaps, be more closely allied than such divergent ruminant types as the elephant, the giraffe, and the gazelle.
Photo by A. S. Rudland & Sons.
NARWHAL.
An Arctic whale, with one or rarely two long spears of bone projecting from the head.
Reference has already been made to the fact that the whales are true mammals, and we must now clearly set before us the justification for separating them from the Fishes—to which any one with a superficial knowledge of their habits and appearance would unhesitatingly assign them—and raising them to the company of other mammals. Let us first separate them from the Fishes. The vast majority of fishes, with some familiar exceptions like the conger-eel, are covered with scales: whales have no scales. The tail of fishes, often forked like that of whales, is set vertically: in whales the tail is set laterally, and for this a good reason will presently be shown. Fishes have anal fins: whales not only have no anal fins, but their so-called pectoral fins differ radically from the fins of fishes. Fishes breathe with the aid of gills: whales have no gills. Fishes, in the vast majority of cases, reproduce their young by spawning, the eggs being left to hatch out either in gravel-beds or among the water-plants, lying on the bottom (as in the case of the herring), or floating near the surface (as in that of the plaice): whales do not lay eggs, but bear the young alive. This brings us to the simple points of resemblance between them and other mammals. When the young whale is born, it is nourished on its mother's milk. This alone would constitute its claim to a place among the highest class. Whales breathe atmospheric air by means of lungs. Hair is peculiarly the covering of mammals, just as scales are characteristic of fishes and feathers of birds. Many whales, it is true, have no hair; but others, if only in the embryonic stage, have traces of this characteristic mammalian covering. It must, moreover, be remembered that in some other orders of mammals the amount of hair varies considerably—as, for instance, between the camel and rhinoceros.
Photo by A. S. Rudland & Sons.
GRAMPUS, OR KILLER.