I. CLASSIFICATION OF THE CETACEA
In order to make clear the relations to each other of the whales and porpoises I have given below a classification and brief diagnosis of the principal groups. The currently accepted subfamilies of the Physeteridæ and Platinistidæ have been omitted for the purpose of simplifying the classification.
Order Cetacea. Whales and Porpoises.
A. Suborder Mystacoceti. Whalebone Whales.
I. Family Balænidæ. Right and Fin Whales.
a. Subfamily Balæninæ. Right Whales.
Head long—skull much arched—whalebone long and very fine—no grooves on ventral surface—no dorsal fin—greatest length, 65 feet.
b. Subfamily Balænopterinæ. Fin Whales.
Head short—skull slightly arched—whalebone short and coarse—grooves on ventral surface—a dorsal fin—greatest length, 87 feet.
II. Family Neobalænidæ. Pigmy Right Whale.
Head short—skull greatly arched—whalebone long, slender and white—no ventral grooves—a dorsal fin—ribs very broad and flat.
III. Family Rhachianectidæ. California Gray Whale.
Head short and moderately arched—whalebone short, coarse and widely spaced—2 to 4 grooves on the throat—no dorsal fin—greatest length, 48 feet.
B. Suborder Odontoceti. Toothed Whales.
I. Family Physeteridæ. Sperm Whales.
Head large and blunt—a single blowhole—40 to 50 teeth in the lower jaw—no functional teeth in upper jaw—a dorsal hump—greatest length, 70 feet.
II. Family Ziphiidæ. The Ziphioid Whales.
Head pointed—snout produced in form of a beak—a single crescent-shaped blowhole on top of head—one or two pairs of functional teeth in lower jaw—no teeth in upper jaw—greatest length, 30 feet.
III. Family Delphinidæ. Porpoises.
a. Subfamily Delphininæ.
Medium size—two or more neck vertebræ joined—single crescent-shaped blowhole on top of head—teeth in both jaws—usually a high dorsal fin—greatest length, 30 feet.
b. Subfamily Delphinapterinæ. White Whale and Narwhal.
Medium size-head small and neck vertebræ all separated—single crescent-shaped blowhole on top of head—no dorsal fin-flippers very broad—greatest length, 20 feet.
IV. Family Platinistidæ. Fresh Water Porpoises.
Small size—neck vertebræ all separate—single crescent-shaped blowhole on top of head—all inhabit fresh or brackish water—greatest length, 12 feet.
II. DIAGNOSES OF THE WHALES DESCRIBED IN THIS BOOK
BLUE WHALE, SULPHURBOTTOM
Balænoptera musculus (Linn.)
Very large size. Average length, 76 feet; maximum length, 87 feet. The pectoral fins are about 15 per cent. of the total length, falcate and bluntly pointed. The dorsal fin is small and variable in form, but usually more or less falcate; it is situated behind the line of the anus. Many ventral folds.
The color of the body is mottled gray, the proportions of light and dark tints varying greatly in different individuals, but the body is usually lightest at the shoulder and between the flippers and the umbilicus. The head is a little darker than the body and unmarked. A few entirely white spots are usually present on the posterior ends of the abdominal folds.
The pectoral fins are gray on the upper surface, except at the tip, and white below. The flukes are plain gray above, and below are marked with fine light and dark gray lines running antero-posteriorly. The dorsal fin is dark gray and the whalebone black.
The rostrum of the skull is very broad with the free margins of the maxillæ convex; the nasal bones are oblong with truncated anterior margins. Vertebral formula: cervicals 7, dorsals 15 (–16), lumbars 14 (–16), caudals 26 (–28). Total, 63–65. Habitat: cosmopolitan.
FINBACK, RAZORBACK
Balænoptera physalus (Linn.)
Large size and very slender form. Average total length, 62 feet; the maximum, 81 feet. The pectoral fins are about 12 per cent. of the total length, lanceolate and pointed. The dorsal fin is moderate in height and falcate; it is situated just behind the line of the anus. Many ventral folds.
The color of the body is dark gray above and white below, the two colors merging imperceptibly into each other on the flanks. The coloration of the head is not bilaterally symmetrical, there being more white on the right side than on the left. The right side of the lower jaw is white and also the anterior third of the whalebone; the left side of the lower jaw and left baleen are dark gray. The gray of the flanks extends obliquely down and back from the pectoral fins toward the flanks, but does not reach the inferior edge of the peduncle, which is white.
The pectoral fins are gray above and white below. The flukes are dark gray above and white below, with a gray posterior margin. The whalebone is gray, striped longitudinally with yellowish white in varying proportions; the anterior baleen on the right side is all yellowish white.
The rostrum of the skull is narrow and pointed with the free margins of the maxillæ nearly straight. The nasal bones are narrow and pointed on the median line anteriorly. Vertebral formula: cervicals 7, dorsals 15 (–16), lumbars 14 (–15), caudals 25 (–26). Total, 61–63. Habitat: cosmopolitan.
SEI WHALE, RUDOLPHI’S RORQUAL
Balænoptera borealis (Lesson)
Moderate size. Average total length, 42 to 43 feet; maximum length, 53 feet. The dorsal fin is large, and falcate; it is situated just anterior to the line of the anus. Many ventral folds.
The color of the head and back is dark gray; on the sides and flanks the gray of the back becomes lighter and the flanks are beautifully marked with wavy gray lines. The throat and breast are white, but a wide dark gray band runs across the belly. The ventral line from the anus to the flukes is gray. The pectoral fins above and below are dark gray, but somewhat lighter on the anterior half of the under side. The flukes above are dark gray like the back, and below are light gray in the ventral portion, becoming darker on the edges. The whalebone is bluish-black with white bristles.
The rostrum of the skull is narrow and triangular with straight sides as in the Finback. The nasal bones are oblong and truncated anteriorly. The first rib is usually bifurcated. Vertebral formula: cervicals 7, dorsals 14 (–13), lumbars 13 (–14), caudals 22 (–23). Total, 56–57. Habitat: cosmopolitan.
HUMPBACK
Megaptera nodosa (Bonn.)
Form massive and ungraceful. Head flat and blunt with dermal tubercles’ along the sides and middle. Ventral folds few and broad. Average total length, 45 feet; maximum length, 55 feet. The pectoral fins are more than one-fourth the entire length with several prominent bunches along the anterior edge. The dorsal fin is low, thick and somewhat falcate, and the flukes are broad with crenate posterior edges.
The color is black with white markings. The head, back and sides are black and the throat and breast to about opposite the pectoral fins are splashed and streaked with white in varying degrees. On the lower lips, sides of the jaw and about the chin, throat and breast are spots, circles and crescents of white; these are probably the scars left by barnacles and other parasites. Between the flippers in the middle of the breast there is usually an irregular transverse patch of white, 10 or 12 inches in diameter.
The flippers are black above with many white spots and circles, and white below except for a broad patch of black at the base. The flukes are normally black above with white spots along the edges; below they are white, spotted and circled with black, except in the basal third, where there is a large black area. The whalebone is dull black, with brownish black bristles.
Skull very broad with an obtuse rostrum. The nasal bones are rather narrow and pointed anteriorly. Vertebral formula: cervicals 7, dorsals 14, lumbars 11 (–10), caudals 21. Total, 53 (–52). Habitat: cosmopolitan.
NORTH ATLANTIC RIGHT WHALE, BLACK WHALE
Eubalæna glacialis (Bonn.)
Form massive. Head about one-fourth the total length and rostrum much arched, with a protuberance near the anterior end, called the “bonnet.” Lower lip very large, and the free margin is more or less sinuous. Pectoral fins very broad and short. No ventral furrows and no dorsal fin. The color is black throughout, with more or less white on the throat and breast in some individuals. Greatest length, 54 feet.
Rostrum of skull very long, narrow and curved. Nasal bones large, broad and oblong. Sternum broad and irregularly triangular. Scapula broader than high. Vertebral formula: cervicals 7, dorsals 14, lumbars 11 (10–12), caudals 23 (–26). Total, 55 (–57). Habitat: in temperate waters in both hemispheres.
BOWHEAD, GREENLAND RIGHT WHALE
Balæna mysticetus (Linn.)
Form massive. Head enormous, exceeding one-third the total length of the whale. Upper jaw greatly arched to accommodate the long whalebone. No “bonnet.” Blowholes elevated and followed by a deep concavity over the “neck.” No ventral furrows and no dorsal fin. The color is black, with some white about the throat and lower lips. The whalebone is black, long and very elastic; in some individuals it reaches a length of 14 feet. Greatest length, 65 feet.
Rostrum of skull long, narrow and remarkably arched. Vertebral formula: cervicals 7, dorsals 12, lumbars 14, caudals 22. Total, 55. Habitat: Arctic waters only; not found in Antarctic.
CALIFORNIA GRAY WHALE, DEVILFISH
Rhachianectes glaucus (Cope)
Form robust. Upper jaw moderately arched. Two to four furrows on throat. No dorsal fin. The color is black, or very dark slate, thickly marked about the snout, lips, chin and jaws with white flecks and small spots. On the sides, breast and belly are many roughly elliptical, irregular grayish markings and white circular spots which are apparently the scars left by barnacles. The amount of white varies greatly with individuals, but is seldom entirely absent. The pectoral fins and flukes are black on both surfaces, with scattered white spots and circles. Average size, 40 feet; maximum size, 49 feet.
Skull with a broad strip of frontal exposed upon the vertex. Nasals very long and broad. Cervical vertebræ all free. Anterior ribs with tubercles, necks and heads. Vertebral formula: cervicals 7, dorsals 14, lumbars 12, caudals 23. Total, 56. Habitat: North Pacific Ocean only.
SPERM WHALE, CACHALOT
Physeter macrocephalus (Linn.)
Size large and form massive. Head blunt. A single S-shaped blowhole at the end of the snout. Forty to 50 teeth in lower jaw. No functional teeth in upper jaw. A prominent “hump” on the back.
The color is slate gray, with some white about the lower jaw and snout, which is crossed in every direction by long white lines (scars). White or gray patches are usually found about the umbilicus. Greatest length, 70 feet.
The bones of the skull are elevated to form a high crest above and behind the nares. The rostrum is very massive and wide, but gradually tapers to the apex, and is concave. Lower jaw very long and narrow. Atlas free, but all the other cervical vertebræ united into a solid mass. Vertebral formula: cervicals 7, dorsals 11, lumbars 8, caudals 24. Total, 50. Habitat: cosmopolitan, in warm currents.
KILLER WHALE, ORCA, GRAMPUS, THRESHER
Orca orca (Linn.)
Form robust. Head pointed. Heavy pointed conical teeth in both jaws. An extremely high dorsal fin. The color is black, with an elliptical white spot on each side of head. The throat and breast are white and there is a trident-shaped area of white on the belly and flanks. A white or grayish patch is usually present just behind the dorsal fin. The flukes above are black, and below white except for a black band on the posterior margins and tips. Greatest length, 30 feet.
Rostrum about equal in length to the cranial part of the skull, broad and flattened above, rounded in front. Teeth usually twelve in each jaw. Vertebral formula: cervicals 7, dorsals 11–12, lumbars 10, caudals 53. Total, 51–52. Habitat: cosmopolitan.
WHITE WHALE, BELUGA, MARSOUIN BLANC
Delphinapterus leucas (Pallas)
Form robust. Head very small and marked off from body by an ill-defined neck. No dorsal fin. Pectoral fins very broad and upturned. The color is pure white in the adult, except for a very narrow band of brownish on the edges of the flukes and flippers. The young are entirely brownish.
Skull rather narrow and elongated. Eight to ten teeth in both jaws—cervical vertebræ all free. Vertebral formula: cervicals 7, dorsals 11, lumbars 9, caudals 23. Total, 50. Habitat: North Atlantic and North Pacific.
BLACKFISH, PILOT WHALE, CA’ING OR GRINDHVAL
Globicephalus melas (Traill)
Form robust. Head large and very round. Dorsal fin thick and triangular. Pectoral fins very long and narrow.
The color is black throughout, except for a narrow fountain-shaped area of white on the throat, breast and belly. Greatest length, 30 feet.
Skull broad and depressed. Premaxillæ strongly concave in front of nares. Vertebral formula: cervicals 7, dorsals 11, lumbars 12–14, caudals 28–29. Total, 58 or 59. Habitat: North Atlantic Ocean.
BOTTLENOSE PORPOISE
Tursiops truncatus (Mont.)
Head produced in the form of a beak. Strong teeth in both jaws. A well-developed dorsal fin.
The color is dark gray on the head, back and sides, and the throat, breast and belly are white. Average length, 8 feet; greatest length, 12 feet.
Rostrum tapering. Palate not grooved. Symphysis of mandible short. Forty to 50 teeth. Vertebral formula: cervicals 7, dorsals 13, lumbars 17, caudals 27. Total, 64. Habitat: North Atlantic Ocean.
III. THE SKELETON OF THE CETACEA
The skeletons of whales and porpoises are so frequently preserved in museums that, for the benefit of those who wish to understand more fully the Cetacea, a brief general description of the osteology is given below. Unfortunately, however, it is impossible to present the subject except in semi-technical language.
The bones of the Cetacea are comparatively light and fragile, the hard, shell-like exterior being thin and the interior filled with spongy “cancellous tissue” which is considerably impregnated with oil. In structure they are exactly opposite to those of the Sirenia (the aquatic mammalian order including the sea cows, or manatees, and the dugongs), which have very heavy solid bones of almost flinty hardness. Cetacean bones are easily affected by weather, and if exposed to the sun, rain and wind for a comparatively short time the hard exterior becomes white and chalk-like.
The whale’s skeleton is highly modified in adaptation to an aquatic existence and is very distinctive of the cetacean order. In a general view it is seen to be greatly elongated, the skull is pointed, the fore-limbs are short and flat and the hind-limbs are represented by nodules of bone; all these accompany a fish-like body which offers little resistance to its passage through the water.
The skull is perhaps more greatly modified than any other portion of the skeleton, and if a trained anatomist who had not studied the Cetacea were to examine a whale’s skull, he would probably be at a loss to identify correctly its parts. The brain case is small and rounded, the eyes are situated far back and the facial portion greatly elongated. The back of the brain case is formed by an extraordinarily developed supra-occipital bone which extends forward and upward to meet the frontal, entirely excluding the parietals from the summit of the skull. The nostrils have rotated backward and upward and are almost vertical instead of horizontal as in other mammals; thus the nasal bones are greatly reduced in size.
The skull of a toothed whale in general appearance is quite unlike that of a whalebone whale; the nasals are very small, and the maxillæ, premaxillæ and frontals meet above the nostrils to form a bony ridge which is sometimes developed into an extraordinary crest. In some cases the crest overhangs the blowholes and is asymmetrical, the right side being much more strongly developed than the left.
The facial portion, or rostrum, of the right whales is narrow and greatly arched, but in the Balænopteras it is wide and flat; in the toothed whales it may be either wide and concave, as in the Physeteridæ, or narrow and beak-like as in the Ziphiidæ and Delphinidæ.
The neck, or cervical, vertebræ of all the Cetacea are exceedingly thin and plate-like and usually either two or three of the entire series are fused. In large-headed species, such as the right whales, the neck is reduced to a minimum and the cervical vertebræ are all joined in a solid mass to bear the weight of the enormous skull.
The remainder of the spinal column, as in all mammals, is divided into dorsal, lumbar and caudal vertebræ. The first series bear ribs and the last, which are those of the “tail region,” may be distinguished by the V-shaped “chevron bones” attached to the lower side of each vertebral body; because of the absence of functional hind-limbs no sacrum is present.
The ribs of the whalebone whales differ from those of other mammals because all but the first two or three have lost the capitulum, or head, and articulate by only the tuberculum to the transverse processes of the vertebræ.
In the baleen whales the sternum, or breast bone, is so reduced that it only articulates with the first pair of ribs, the lower ends of those remaining being free. Thus with the weak attachment of the ribs to the vertebræ and no fastening to the sternum, a loose “thoracic box” is formed, which is capable of great lateral movement as the enormous lungs expand and contract.
In the toothed whales conditions are somewhat different. Many of the ribs have the normal attachment by head and tubercle to the vertebræ and are joined by their lower ends to the sternum, which consists of several pieces; thus the thoracic box is much more rigid than in the baleen whales.
The bones of the fore-limbs of ordinary mammals are present in the cetacean flipper, but they become greatly flattened and overlaid with adipose tissue to form a paddle. In the right whales the five fingers of the mammalian hand are present, but in others one finger has been lost, and the digits are greatly elongated. The scapula, or shoulder blade, is a wide, flat, fan-shaped bone, and the clavicles, or collarbones, have entirely disappeared. The hind-limbs are rudimentary, when present at all, only being represented by bony nodules, and the pelvis is reduced to two spindle-shaped bones quite unlike that of land mammals.
The skeleton of each group of the Cetacea, although similar in general characters, varies enormously in the details of construction, and to anyone interested in osteology will prove a fascinating subject for investigation.
IV. ADAPTATION AS SHOWN BY THE CETACEA
There are many indisputable evidences that whales once lived upon the land and walked upon four legs like ordinary quadrupeds, yet how remarkably different from any land mammal is their present form!
We see that almost all aquatic creatures have torpedo-shaped bodies, which offer the minimum of resistance to their passage through the water. Thus as the whales gradually changed from a terrestrial to an aquatic life their bodies assumed the elongated form essential for successful existence in a liquid medium.
Accompanying this change of bodily shape was the elimination of all unnecessary structures which offered resistance, and the whale’s smooth, soft, hairless skin was one of the results. But the hair of a land mammal acts as a non-conductor, preventing the heat of the blood from being absorbed by the air, and as the whale’s body became naked it was necessary to blanket it with some other protective covering; thus the layer of fat or blubber developed between the skin and the flesh. Fish and amphibians do not need a warm covering because their blood is cold and changes with the temperature of the medium in which they live.
Besides giving warmth to a land mammal, hair acts as a protection for its tender skin; but since a whale lives in the water, where bruises or abrasions are unlikely, such protection is unnecessary. With the loss of hair the sweat and oil glands which are present in the skins of land mammals finally disappeared.
When any creature becomes aquatic it must necessarily develop means for progression through the water, and thus the caudal portion of the whale’s body by degrees expanded into the wide, flat, boneless tail, or flukes. But instead of being vertical to the axis of the body like the tail of a fish, the whale’s flukes are horizontal, obviously to give the animal greater facility in rising to the surface to breathe.
With the development of the flukes there came a change in the whale’s fore-limbs, which were flattened and covered with connective tissue and blubber. The excellent paddles thus formed, while probably of little use in forward motion, assist in rapid turning and act as balancing organs to keep the animal upright in the water. In some species an adipose dorsal fin has also developed as a further balancing aid.
During the development of the flippers and flukes the hind-limbs, which were no longer of use to the whale, became small and weak, sunk into the blubber and finally disappeared altogether, the greatly modified pelvic elements and nodules of bone or cartilage representing the femur alone remaining.
The heads of most cetaceans are long and pointed, acting as a “cut-water,” but one of the most remarkable aquatic adaptations is the position of the nostrils, or blowholes, which open upon the very summit of the head, in either a single or double aperture, instead of at the end of the snout. The cause of this migration of the nostrils is obvious, for in this position the blowholes first appear at the surface and the whale can begin to breathe while the rest of its body is yet under water.
In all cetaceans the facial portion of the skull is greatly elongated, and especially in the Mystacoceti the mouth is exceedingly large to accommodate the baleen, which hangs in two parallel rows from the upper jaw. Probably no mammalian adaptation for the securing of food is more remarkable than the whale’s baleen. It is almost unbelievable that an animal which once had teeth could, as its food changed, replace them by a complicated straining apparatus such as the whalebone. The baleen is an epidermal growth and is in reality merely an exaggeration of the transverse ridges present in the mouths of land mammals.
We know that the Mystacoceti at one time had teeth, for in fœtal whales two sets of minute teeth are present under the skin, corresponding to the “milk” and “permanent” dentition of ordinary mammals, but these disappear before the baleen begins to develop.
Another interesting feeding adaptation is present in the throat of the whale. The nostrils, instead of opening into the back of the mouth, as in land mammals, are directly connected with the lungs by a prolongation of the “windpipe” called the epiglottis, which entirely shuts off the whale’s breathing passage from the mouth. Thus the animal can swallow its food beneath the surface without danger of strangulation through getting water into its lungs.
When whales lived upon the land external ears were necessary, but as they became completely aquatic such “sound collectors” were not only of no more use but highly undesirable, because, like the useless hind-limbs, they offered additional resistance to the water; therefore the external ears were lost, but their muscles still remain about the minute ear-orifices of the present-day Cetacea.
The internal modifications which the whales underwent as they assumed an aquatic existence are fully as remarkable as the external changes. In the section on osteology it has been explained how, in living cetaceans, the entire skeleton is loosely articulated so that great flexibility and freedom of movement is given to the body, how the neck is shortened and the vertebræ have become thin and closely packed together to support the large head, and how the breast bone is reduced and the ribs so loosely articulated to the vertebral column that the huge lungs have full power of expansion. All these are necessary modifications of the mammalian skeleton which have been caused by the change from a terrestrial to an aquatic existence.
The lungs of the Cetacea are unlobulated and of extraordinary size; the diaphragm, the muscular partition which separates the thoracic from the abdominal cavity, is oblique, and the brain greatly convoluted and of a high type; the brain is especially notable for the loss of the olfactory, or smelling portions, which are of no use to an aquatic mammal.
Thus it is apparent in a review of only the most obvious changes what a wonderful example of adaptation to environment is furnished by the Cetacea.