_THE DUGONG, MANATEES, WHALES, PORPOISES, AND DOLPHINS._
BY F. G. AFLALO, F.Z.S.
----
THE DUGONG AND MANATEES.
These curious creatures, which seem to have been the basis of much of the
old mermaid legend, have puzzled many eminent naturalists. Before they were
placed in an order by themselves, Linnæus had classed them with the Walrus,
Cuvier with the Whales, and another French zoologist with the Elephants.
They are popularly regarded as the cows of the sea-pastures. Their habits
justify this. I have often watched dugongs on the Queensland coast browsing
on the long grasses, of which they tear up tussocks with sidelong twists of
the head, coming to the surface to breathe at short intervals.
Omitting the extinct Rhytina, otherwise known as Steller's Sea-cow, which
was exterminated in the Bering Strait not very long after civilised man had
first learnt of its existence, we have to consider two distinct groups, or
genera, of these sirenians. The DUGONG is the representative of the first,
and the two MANATEES belong to the other.
[Illustration: _Photo by A. S. Rudland & Sons._
DUGONG.
A vegetable-feeding sea-mammal from the Indian Ocean and North Australian
waters.]
The dugong is found on the coasts of Northern Australia, in many parts of
the Indian Ocean (particularly off Ceylon), and in the Red Sea. It is
easily distinguished, by even superficial observation, from the manatees.
Its tail is slightly forked, somewhat like that of the whales: the tail of
manatees, on the other hand, is rounded. The dugong's flippers, to which we
also find a superficial resemblance in those of the whale, show no traces
of external nails: in those of the manatees, which show projecting nails,
there is a considerable power of free movement (the hands being, in fact,
used in manipulating the food), which is not the case in the limbs of the
whale. The body of the dugong is almost smooth, though there are bristles
in the region of the mouth: that of the manatees is studded with short
hairs. The male dugong has two large tusks: in neither sex of the manatees
are such tusks developed. Finally, a more detailed examination of the
skeletons would reveal the fact that, whereas the dugong has the usual
seven bones in the neck, that of the manatees has only six.
[Illustration: _Photo by A. S. Rudland & Sons._
AMERICAN MANATEE.
Found in the Amazons River. The Manatees differ remarkably from the Dugong
in the number and structure of their teeth.]
When we come to the Whales, we shall encounter that very characteristic
covering known as "blubber"; and, though it is present in smaller quantity,
these sirenians have blubber as well. Complex stomachs they also have, like
the whales, only in their case both the nature of the food and the
structure of the teeth point clearly to a ruminating habit, which, for
reasons that will be given in the right place, seems inadmissible in the
whales. In both dugong and manatees the mouth is furnished with singular
horny plates, the precise use of which does not appear to have been
satisfactorily determined; and the upper lip of the manatee is cleft in two
hairy pads that work laterally. This enables the animal to draw the grass
into its mouth without using the lower lip at all.
In their mode of life the dugong and manatees differ as widely almost as in
their appearance; for the former is a creature of open coasts, whereas the
manatees hug river-estuaries and even travel many miles up the rivers. Of
both it has been said that they leave the water at night, and the manatees
have even been accused of plundering crops near the banks. The few,
however, which have been under observation in captivity have always been
manifestly uncomfortable whenever, by accident or otherwise, the water of
their tank was run off, so that there is not sufficient reason for
believing this assertion.
This group of animals cannot be regarded as possessing any high commercial
value, though both natives and white men eat their flesh, and the
afore-mentioned rhytina was, in fact, exterminated solely for the sake of
its meat. There is also a limited use for the bones as ivory, and the
leather is employed on a small scale,--a German writer has, in fact, been
at great pains to prove that the Tabernacle, which was 300 cubits long, was
roofed with dugong-skin, and the Red Sea is certainly well within the
animal's range.
THE WHALES, PORPOISES, AND DOLPHINS.
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.
[Illustration: _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.
[Illustration: _Photo by A. S. Rudland & Sons._
GRAMPUS, OR KILLER.
A carnivorous cetacean with large teeth, often found in British seas.]
Having, then, shown that whales are mammals, we must now determine the
chief features of the more typical members of the order. The extremities of
whales are characteristic: a large head, occupying in some species as much
as one-third of the total length; and the afore-mentioned forked, or lobed,
tail set laterally. The flippers, which bear only a slight resemblance to
the pectoral fins in fishes, are in reality hands encased in
swimming-gloves. In some whales these hands are five-fingered, in others
the fingers number only four, but many of the fingers contain more bones
than the fingers of man. In some whales we find a dorsal fin, and this, as
also the flippers, acts as a balancer. In no whale or porpoise is there any
external trace of hind limbs, but the skeleton of some kinds shows in
varying stages of degradation a rudimentary bone answering to this
description. Perhaps however, the most distinctive feature of whales is the
blow-hole, situated, like the nostrils of the hippopotamus, on the upper
surface of the head, and similarly enabling the animal to breathe the air
without exposing much of its head above the surface of the water. The
blow-hole (or blow-holes, for whalebone-whales have two) may be said to
take the place of nostrils as regards the breathing, though perhaps no
sense of smell is included in its functions. In the Sperm-whale, or
Cachalot, there is a single S-shaped blow-hole near the end of the snout.
The well-known spouting of whales is merely the breathing out of warm
vapour, which, on coming in contact with the colder air--and it should be
remembered that most whaling is carried on in the neighbourhood of
icebergs--condenses in a cloud above the animal's head. I have seen many a
sperm-whale spout, and the cloud of spray, often mixed with a varying
volume of water if the whale commences to blow before its blow-hole is
clear of the surface, drifts forward over the forehead. This is due to the
forward position of the blow-hole. I never to my knowledge saw a
whalebone-whale spouting, but its double jet is said to ascend vertically
over its back, and this would in like manner be accounted for by the more
posterior position of the blow-holes. Having filled its lungs, which are
long and of simple structure, with fresh air, in enormous draughts that
fill the great cavities of its chest, the whale sinks to the depths. There,
in ordinary circumstances, it will lie for a quarter of an hour or more,
but the pain of the harpoon and the knowledge that there is danger at the
surface may keep it below for as much as an hour. When it has to breathe
again, a few powerful strokes from the laterally set tail suffice to bring
it quickly to the surface. This is not the place for a detailed anatomy of
the whale, but no one can fail to notice with admiration such parts of its
equipment for the battle of life as the structure of its windpipe, which
enables it to breathe with comfort with its mouth full of water, the
complicated network of blood-vessels that ensures the slow and thorough
utilising of all the oxygen in its lungs while it remains at the bottom,
and the elastic cushion of blubber that makes this gigantic animal
indifferent to extremes of pressure and temperature. Thanks mainly to its
coat of blubber, the whale exists with equal comfort at the surface or
hundreds of fathoms below it; in the arctic or in tropical seas.
[Illustration: _Photo by A. S. Rudland & Sons._
SHORT-BEAKED RIVER-DOLPHIN.
In this type the head is produced into a beak, supported in the upper jaw
by a mass of ivory-like bone.]
It is not perhaps in keeping with the plan of this work that we should
consider in detail the soft parts of the whale's inside. One or two parts
of its feeding and digestive mechanism may, however, offer some points of
passing interest. The complex stomach, which is divided into chambers, like
that of the ruminants already described, has suggested that the latter
function may in a modified process be performed by whales. It is, however,
evident that the teeth of toothed whales are in no way adapted to the act
of mastication, which is inseparable from any conception of ruminating,
while the toothless whales have as complicated a stomach as the rest. Mr.
Beddard, writing on the subject in his interesting "Book of Whales," takes
the more reasonable view that the first chamber of the stomach of whales
should be regarded rather as a storehouse in which the food is crushed and
softened. The teeth of whales, the survival of which in the adult animal
offers the simplest basis of its classification under one or other of the
two existing groups, or sub-orders, are essentially different from the
teeth of many other kinds of mammals. It cannot, perhaps, be insisted that
the distinctive terms employed for these two categories of whales are
wholly satisfactory. For instance, the so-called "toothless" whales have
distinct teeth before birth, thus claiming descent from toothed kinds. On
the other hand, the so-called "toothed" whales are by no means uniformly
equipped in this respect, some of the porpoises having as many as
twenty-six teeth, distributed over both jaws, while the bottlenoses have no
more than two, or at most four, and these in the lower jaw only. Only the
lower jaw, in fact, of the great sperm-whale bears teeth that are of any
use, though there are smaller and functionless teeth in the gums of the
upper. The teeth of whales, by the way, are not differentiated like our
canines and molars, but are all of one character. Although, in "toothless"
whales, the foetal teeth disappear with the coming of the baleen, or
whalebone, the latter must not, in either structure or uses, be thought to
take their place. The plates of whalebone act rather as a hairy strainer.
Unless we seek a possible analogy at the other end of the mammalian scale,
in the Australian duckbill, the feeding of the whalebone-whales is unique.
They gulp in the water, full of _plankton_, swimming open-mouthed through
the streaks of that substance. Then the huge jaws are closed, and the
massive tongue is moved slowly, so as to drive the water from the angles of
the mouth through the straining-plates of baleen, the food remaining
stranded on these and on the tongue. The size and number of the
baleen-plates appear to vary in a degree not yet definitely established;
but there may, in a large whale, be as many as between 300 and 400 on
either side of the cavernous mouth, and they may measure as much as 10 or
12 feet in length and 7 or 8 feet in width.
[Illustration: _Photo by A. S. Rudland & Sons._
SOWERBY'S BEAKED WHALE.
One of the rarest of British whales, and very scarce elsewhere. It probably
inhabits the open seas.]
An enumeration of such whales and porpoises and dolphins as have at one
time or other been stranded on the shores of the British Isles may serve as
an epitome of the whole order. Only one interesting group, in fact--the
River-dolphins of the Ganges and Amazons--is unrepresented in the British
list. Whales, either exhausted or dead, are periodically thrown up on our
coasts, even on the less-exposed portions--one of the most recent examples
in the writer's memory being that of a large specimen, over 60 feet long,
stranded on the sands near Boscombe, in Hampshire, and the skeleton of
which at present adorns Boscombe Pier. It was one of the rorquals, or
finbacks, probably of the species called after Rudolphi; but the skeleton
is imperfect, though its owner, Dr. Spencer Simpson, appears to have
preserved some details of its earlier appearance. It should be remembered
that many of the following can only be regarded as "British" with
considerable latitude, the records of their visits being in some cases as
rare as those of the rustic bunting and red-necked nightjar among birds, or
of the derbio and spotted dragonet among fishes.
British zoologists, however, usually include the
following:--WHALEBONE-WHALES: Southern Right-whale; Humpback; Finbacks, or
Rorquals. TOOTHED WHALES: Sperm-whale, or Cachalot; Narwhal; Beluga, or
White Whale; Grampuses; Beaked Whale; Broad-fronted Whale; Cuvier's Whale;
Sowerby's Whale; Pilot-whale; Porpoise; Dolphin; White-sided Dolphin;
White-beaked Dolphin; Bottlenose.
A selection may therefore be made of five of the most representative of
these species--the SOUTHERN WHALE, the CACHALOT, the NARWHAL, the PORPOISE,
and the DOLPHIN.
The SOUTHERN WHALE, which, in common with the closely allied polar species,
whaling-crews call "right," seeing that all other kinds are, from their
point of view, "wrong," is probably the only right-whale which has ever
found its way to our shores. Some writers include the Greenland
Right-whale, but their authority for this is doubtful. It is said to grow
to a length of at any rate 70 feet, though 55 feet would perhaps be more
common for even large specimens. In colour it is said to be dark above,
with a varying amount of white or grey on the flippers and under-surface.
The head and mouth are very large, occupying in some cases one-third of the
total length, and the baleen-plates measure as much as 8 or 10 feet in
length and 5 or 6 feet in width. The species has no back-fin, but there is
a protuberance on the snout, known technically as the "bonnet." This whale
appears to give birth to its single calf some time in the spring months,
and the mother shows great affection for her offspring. The HUMPBACK is
distinguished from the right-whales externally by its longer flippers and
the prominence on its back, and internally by the fluted skin of the
throat. The FINNERS, or RORQUALS, have a distinct back-fin. They feed on
fishes and cuttles, and I have more than once known a rorqual, which looked
fully 50 feet long (comparing it roughly with my 24-foot boat), to swim
slowly round and round my lugger, down on the Cornish coast, puffing and
hissing like a torpedo-boat on its trial trip, rounding up the pilchards in
a mass, and every now and then dashing through them open-mouthed with a
terrific roar, after several of which helpings it would sink out of sight
and not again put in an appearance.
[Illustration: _Photo by A. S. Rudland & Sons._
COMMON PORPOISE.
From 4 to 5 feet long. It lives in "schools," or companies, and pursues the
herrings and mackerel.]
The SPERM-WHALE, or CACHALOT, may serve as our type of the toothed whales.
It attains to the same great dimensions as the largest of the whalebone
group. A more active animal for its size could scarcely be conceived; and I
have seen one, in the Indian Ocean, fling itself three or four times in
succession out of water like a salmon, striking the surface each time as it
fell back with a report like that of a gun. No one appears to have
explained whether performances of this sort are due to mere playfulness,
or, as seems more probable, to the attacks of parasites or such larger
enemies as sharks or "killers." I have also seen four thresher-sharks
leaping out of water, and falling with a loud blow on the whale's back; but
the victim lay quite still in this case, and may in fact have been worn out
before we came upon the scene. I wish to add that I took the word of the
skipper, himself an old whaling-captain, for their identity as threshers.
The dazzling sun shone full on them, and on the sea between, and it was
impossible, even with the ship's telescope, to recognise them with any
accuracy. The cachalot has a very different profile from what any one who
had seen only its skull in a museum would be led to expect, for the
sperm-cavity in the forehead is not indicated in the bones. The structure
of the head enables the animal to drop the lower jaw almost at right angles
to the upper; and Mr. Frank Bullen quotes, in his fascinating "Cruise of
the Cachalot," the current belief that it does so to attract its prey by
the whiteness of its teeth and palate. Although both fishes and cephalopods
are very curious, even to their own destruction, it is doubtful whether the
whale could not catch its food more rapidly by swimming open-mouthed
through the acres of floating squid encountered all over the warmer waters
of the ocean.
[Illustration: _Photo by A. S. Rudland & Sons._
ELLIOTT'S DOLPHIN.
One of the commoner Indian species.]
[Illustration: _Photo by A. S. Rudland & Sons._
RISSO'S DOLPHIN.
About 13 feet in length, found in almost all oceans.]
The NARWHAL, an arctic type, may be distinguished from all other cetaceans
by the single spiral tusk in the left side of the head of the male.
Sometimes the right tusk grows as well, and either may attain a length of
as much as 8 feet; but in the female both teeth remain undeveloped.
The COMMON PORPOISE of our own seas, distinguished by its rounded head from
the equally common beaked dolphin, is too familiar to need much
description. It grows to a length of 5 or 6 feet, and is dark in colour on
the back and white beneath. Its conspicuous back-fin is always recognisable
when it gambols with a herd of its fellows; and a line of these sea-pigs, a
mile or so in length, is no uncommon sight, their presence inshore being
indicative on some parts of the coast of the coming of east wind. The
porpoise, which has, like many of its group, teeth in either jaw, is a
voracious feeder, preying in estuaries on salmon and flounders, and on more
open parts of the coast on pilchards and mackerel. It is occasionally a
serious nuisance in the Mediterranean sardine-fisheries, and I have known
of the fishermen of Collioure, in the Gulf of Lyons, appealing to the
French Government to send a gunboat from Toulon that might steam after the
marauders and frighten them away. One of the most remarkable cases of a
feeding porpoise that I can recall was that of one which played with a
conger-eel in a Cornish harbour as a cat might play with a mouse, blowing
the fish 20 or 30 feet through the air, and swimming after it so rapidly as
to catch it again almost as it touched the water.
[Illustration: _Photo by A. S. Rudland & Sons._
BOTTLE-NOSED DOLPHIN.
From 8 to 9 feet long, found from the Mediterranean to the North Sea.]
The DOLPHIN, which is in some seasons as common in the British Channel as
the more familiar porpoise, is distinguished by its small head and long
beak, the lower jaw always carrying more teeth than the upper. It feeds on
pilchards and mackerel, and, like the porpoises, gambols, particularly
after an east wind, with its fellows close inshore. There are many other
marine mammals somewhat loosely bracketed as dolphins. RISSO'S DOLPHIN, for
instance, a rare visitor to our coasts, has a striped skin, and its jaws
are without teeth, which distinguish it from the common dolphin and most of
the others. It cannot therefore feed on fishes, and most probably eats
squid and cuttle-fish. The BOTTLE-NOSED DOLPHIN, a species occurring in the
greatest numbers on the Atlantic coast of North America, is regularly
hunted for its oil. HEAVYSIDE'S DOLPHIN, which hails from South African
waters, is a smaller kind, chiefly remarkable for the curious distribution
of black and white on its back and sides.
[Illustration: _Photo by A. S. Rudland & Sons._
HEAVYSIDE'S DOLPHIN.
A small, peculiarly coloured species from the Cape.]
A word must, in conclusion, be said on the economic value of the whales.
Fortunately, as they are getting rarer, substitutes for their once
invaluable products are being from time to time discovered, and much of the
regret at their extermination by wasteful slaughter is sentimental and not
economic. For whalebone it is not probable that a perfect substitute will
ever be found. It therefore maintains a high price, though the former
highest market value of over £2,000 per ton has fallen to something nearer
the half. The sperm-oil from the sperm-whale, and the train-oil from that
of the right-whales, the spermaceti out of the cachalot's forehead and the
ambergris secreted in its stomach, are the other valuable products.
Ambergris is a greyish, fatty secretion, caused by the irritation set up in
the whale's inside by the undigested beaks of cuttle-fish. Its market price
is about £5 per ounce. A lump of 240 lbs. sold for nearly £20,000.
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