Natural History of the Mammalia of India and Ceylon Part 47

I am largely indebted to Dr. Anderson for information concerning it, for he has not only most carefully watched the habits of this curious animal, but has most exhaustively described its anatomy in his 'Anatomical and Zoological Researches.' It is found in the Hooghly, chiefly in the cold weather, migrating during the hot and rainy season; at least so it was supposed, and Dr. Cantor conjectured that at such times it visited the sea, but this has been proved to be not the case. The _soosoo_ never leaves fresh water; and it is in the river during the rains, for fishermen catch it in their nets, but it is hardly ever seen at that time. It rises so as to expose the blow-hole only, and the rush of the swollen waters prevents the peculiar sound of respiration being heard. But in the cold weather, when the river is calm, the ear is attracted at once by the hissing puff of expiration, and the animal may be seen to bound almost out of the water. Dr. Anderson had one alive in captivity for ten days, and carefully watched its respirations. "The blow-hole opened whenever it reached the surface of the water. The characteristic expiratory sound was produced, and so rapid was the inspiration that the blow-hole seemed to close immediately after the expiratory act."

He states that "the respirations were tolerably frequent, occurring at intervals of about one-half or three-quarters of a minute, and the whole act did not take more than a few seconds for its fulfilment." But it is probable that in a free state and in perfect health the animal remains longer under water. It has certainly been longer on several occasions when I have watched for the reappearance of one in the river. The food of the Gangetic dolphin consists chiefly of fish and crustacea; occasionally grains of rice and remains of insects are found in the stomach, but these are doubtless, as Dr.

Anderson conjectures, in the fish swallowed by the dolphin. The period of gestation is said to be eight to nine months, and usually only one at a time is born, between April and July. The young are sometimes caught with their mothers, and are said to cling by holding on by the mouth to the base of the parent's pectoral fins. "The flesh and blubber are occasionally eaten by many of the low caste Hindus of India, such as the Gurhwals, the Domes of Jessore and Dacca districts, the Harrees, Bourees, Bunos, Bunpurs, Tekas, Tollahas, the Domes of Burdwan and Bhagulpore, who compare it to venison; also by the Teewars and Machooas of Patna, the Mussahars of Shahabad, the Gourhs and Teers of Tirhoot, and the Mullahs of Sarun. In the North-west Provinces about Allahabad, the Chumars, Pa.s.sees, Kooras, Khewuts or Mullahs, have rather a high estimate of the flesh, which they a.s.sert resembles turtle. The Koonths of Benares, Phunkeahs, Natehmurrahs, and Buahoas of Moradabad, and also such gipsy tribes as the Sainsees, Kunjars and Hubbossahs, in the neighbourhood of Meerut, do not despise it. In the Punjab we find the Choorahs, Dhapels, Sainsees, Budous, and Burars eating the flesh; and in Sind the Kehuls.

The Moras, a tribe of Mahomedan boatmen who lead a wandering life on the streams in the Punjab and in Sind, subsist on the dolphin when by good chance they catch one; this is also the case with the Cacharies and the Nagas of a.s.sam. The Sansee women on the Indus eat the flesh under the idea that it makes them prolific. All along the Ganges, Brahmahputra, and Indus, the oil is universally considered as of great value as an embrocation in rheumatism and for giving much strength when rubbed on the back and loins. But many other animal oils, such as those of various species of turtle, the crocodile, and the pelican, have a similar reputation. It is said to be of a very penetrating nature, and, owing to this property, it is highly prized for preserving leather, such as harness, &c. The illuminating powers of this oil are said to be very high." (Anderson's 'Anatomical and Zoological Researches.')

Jerdon gives, on the authority of Blyth, another species, _Platanista Indi_, or the Indus porpoise, but Dr. Anderson has conclusively proved that this is identical with the Gangetic dolphin.

The dent.i.tion of the _soosoo_ is most curious. The perfect tooth in the young animal is sharp and pointed, but as the creature advances in age the fangs get broader, and the point wears down, till in old age the crown is so worn as to leave but a bony lump in its place.

_GENUS ORCELLA--THE ROUND-HEADED RIVER DOLPHINS_.

The generic characteristics of these dolphins are, according to Dr.

Anderson, as follows: "Head globular; dorsal fin low, situated behind the middle of the body; pectoral fins oval, about one-sixth the length of the animal; teeth conical, large, and fewer in the lower than in the upper jaw, thirteen to seventeen teeth in the upper and twelve to fourteen teeth in the lower jaw; skull beaked; beak broad at the base, anteriorly pointed; premaxillary not much laterally dilated, bearing one tooth; vertebrae sixty-two to sixty-three; first two cervical vertebrae ankylosed; lumbar transverse process moderately long; vertebrae ribs twelve to thirteen, with one or two free ribs; pelvic bones opposite thirty-fifth and thirty-sixth vertebrae."

These are the dolphins which were procured by Mr. Blyth in the Hooghly, and were supposed by him to be the young of the ca'ing whale (_Globicephalus_), which idea has also been adopted by Jerdon; but it has been since proved that the skeletons prepared from these supposed young whales are those of adults fully matured, and not of young animals, which have certain resemblances to _Globicephalus_ as well as to the killer whales, _Orca_, from which the generic name has been derived, but yet was undoubtedly distinct. The killer whales have a very high dorsal fin in the middle of the back, with very large pectoral flippers as broad as long; in _Orcella_ the back fin is low and behind the middle of the body, and the pectoral fin is only half as broad as long. In the ca'ing whale the back fin is more towards the shoulders, and the flippers are long and narrow; the genus _Orcella_ in fact seems to be intermediate between the dolphin and the ca'ing whale, combining the head of _Globicephalus_ with the body of _Delphinus_. Dr. Anderson, however, points out further differences than the external ones I have above alluded to. _Orca_, he says, is distinguished by a "more powerfully built skeleton, with considerably fewer vertebrae, there being only a maximum of fifty-three in it to a maximum of sixty-three in _Orcella_." In _Orca_ generally four or five cervical vertebrae are ankylosed as in the cachelots, but in the two species of _Orcella_ only the atlas and axis are joined. "In the killers and ca'ing whales the ribs are transferred to the transverse processes at the seventh dorsal, whilst in _Orcella_ the transference does not take place until the eighth." The skull resembles that of _Orca_ in the breadth of the upper jaw being produced by the maxillaries, whereas in _Globicephalus_ this effect is caused by the premaxillaries. The teeth resemble the killer's.

As I have said so much about the killer whale, I may digress a little to explain what it is, though it is not a denizen of the Indian seas.

It is to the Cetacea what the shark is to fishes--a voracious tyrant with a capacious mouth, armed with formidable teeth. It hesitates not to attack the largest sperm and Greenland whales, and the smaller whales, porpoises and seals will spring out of water and strand themselves on sh.o.r.e in terror at its approach. It ranges from twenty to thirty feet in length, and is of so gluttonous a character that in one recorded case a killer had been found choked in the attempt to swallow a _fifteenth_ seal, the other fourteen, with thirteen porpoises, being found in its stomach!

According to Scammon three or four of them do not hesitate to grapple with the largest baleen whale; and, as described by Dr. Murie, "the latter often, paralysed through fear, lie helpless and at their mercy.

The killers, like a pack of hounds, cl.u.s.ter about the animal's head, breach over it, seize it by the lips, and haul the bleeding monster underwater; and, should the victim open its mouth, they eat its tongue." In one instance he relates that a Californian grey whale and the young one were a.s.saulted; the _Orcas_ killed the latter, and sprang on the mother, tearing away large pieces of flesh, which they greedily devoured.

"These brutes have been known to attack a white-painted herring boat, mistaking it for a beluga; and it is stated that occasionally they will boldly lay siege to whales killed by the whalers, almost dragging them perforce under water. Near some of the Pacific sealing grounds they continually swim about, and swoop off the unwary young; even the large male sea-lions hastily retreat ash.o.r.e and give these monsters a wide berth. The walrus also, with his powerful tusks, cannot keep the killers at bay, especially if young morses are in the herd. The cubs on such occasions will mount upon the mother's back for refuge, clinging for dear life, but the _Orca_, diving, comes suddenly up with a spiteful thud, and the cub, losing its balance, falls into the water, when in an instant it is seized by the remorseless whales." The speed of the killer whale is immense, as may be supposed when it can overtake the swift dolphins, which it catches and swallows alive. It has also been seen chasing salmon up the mouths of rivers.

The genus _Orcella_ seems to come in between the sea and river dolphins, although _Orcella fluminalis_ of Dr. Anderson is a purely fluviatile animal, which apparently never goes out to sea.

NO. 258. ORCELLA BREVIROSTRIS.

_The Short-nosed Round-headed River Dolphin_.

HABITAT.--The estuaries of the Ganges and Brahmaputra rivers.

DESCRIPTION.--"The head is convex from the blow-hole to the upper lip, but its sides immediately below the angle of the mouth are somewhat anteriorly convergent, but rounded; the gape posteriorly has a long upward curve; the eye, which is well developed, is near the angle at the gape, and in the adult is placed about one inch above it, with a slightly downward slope; the ear is nearly on the same level as the angle of the mouth, but is extremely small, crescentic, and not measuring more than 0.12 inch in diameter. The posterior margin of the blow-hole is immediately behind the anterior angle of the eye; the blow-hole is crescentic and unsymmetrical, being more to the left than to the right side; there are two slight eminences about one inch behind the blow-hole; the construction of the neck occurs below the ear and slightly behind it" (Anderson's 'Anatomical and Zoological Researches,' p. 370). The other characteristics are triangular flippers half as broad as long. The back fin rises behind the centre of the back; it is comparatively small, falcate, curved over the top to a blunt point, and concave behind. The line of the back is sharp from this fin down to the tail. The ventral line is the same for some inches behind the a.n.u.s. The colour is dark slaty-blue above, almost black, a little paler below, without any streaks or marks, such as in _O. fluminalis_ and Risso's grampus.

SIZE.--From snout to caudal notch, about 7 feet.

I cannot find much on record concerning the habits of this dolphin, and my own acquaintance with it is too limited for me to afford much original information.

NO. 259. ORCELLA FLUMINALIS (_Anderson_).

_The Fresh-water Round-headed Dolphin_.

HABITAT.--The Irrawaddy river; Burmah.

DESCRIPTION.--This differs from the last in a "rather smaller, lower, and more falcate dorsal fin, its more pointed and less anteriorly bulging head, and rather shorter and broader pectoral fins"

(_Anderson_). The colour is a pale bluish above, and white underneath, with numerous streaks, as in Risso's grampus.

SIZE.--From 7 to 7-1/2 feet from snout to fork of tail.

Dr. Anderson, who has fully described this species, says that he has "never observed it in tidal waters, so that it is even more strictly fluviatile than the Gangetic dolphin. From a little below Prome to as far up as Bhamo, which is about 550 miles, as the crow flies, from the sea, these animals abound. It is a.s.serted by the Shans of Upper Burmah that these dolphins are not to be found beyond a point thirty miles above Bhamo, where the course of the river is interrupted by rocks, and which they style _Labine_ or Dolphin Point, from the circ.u.mstance that, according to them, it is the residence of certain _Nats_, who there impose so heavy a toll on dolphins as to deter them from proceeding upwards."

This dolphin is somewhat like its marine cousins, being fond of gambolling round the river steamers. Solitary ones are seldom met with, usually two or three being together. When they rise to breathe the blow-hole is first seen; then, after respiration, the head goes down, and the back as far as the dorsal fin is seen, but rarely the tail flippers. They rise to breathe every 70 to 150 seconds, and the respiratory act is so rapid that it requires a very expert marksman to take aim and fire before the animal disappears.

Dr. Anderson says: "I have observed some of them disporting themselves in a way that has never yet been recorded of _Cetacea_, as far as I am aware. They swam with a rolling motion near the surface, with their heads half out of the water, and every now and then nearly fully exposed, when they ejected great volumes of water out of their mouths--generally straight before them; but sometimes nearly vertically. The sight of this curious habit at once recalled to me an incident in my voyage up the river, when I had been quite baffled to explain an exactly similar appearance seen at a distance, so that this remarkable habit would appear to be not uncommonly manifested.

On one occasion I noticed an individual standing upright in the water, so much so that one-half of its pectoral fins was exposed, producing the appearance against the background as if the animal was supported on its flippers. It suddenly disappeared, and again, a little in advance of its former position, it bobbed up in the same att.i.tude, and this it frequently repeated. The Shan boatmen who were with me seemed to connect these curious movements with the season--spring--in which the dolphins breed."

A similar thing has been noticed in the case of marine dolphins off the coast of Ceylon by Mr. E. W. H. Holdsworth, whose observations confirm the opinion of the Shan boatmen. (See 'P. Z. S.' 1872, p.

586.)

"The food of the Irrawady dolphin is apparently exclusively fish.

The fishermen believe that the dolphin purposely draws fish to their nets, and each fishing village has its particular guardian dolphin, which receives a name common to all the fellows of his school, and it is this supposition that makes it so difficult to obtain specimens of this cetacean. Colonel Sladen has told me that suits are not unfrequently brought into the native courts to recover a share in the capture of fish in which a plaintiff's dolphin has been held to have filled the nets of a rival fisherman" (_Anderson_). This reminds me that in the surveying voyage of the _Herald_, as related by Mr.

H. Lee, the natives of Moreton Bay entreated the seamen not to shoot their tame porpoises, which helped them in their fishing.

_GENUS DELPHINUS--THE MARINE DOLPHINS_.

These are characterised by a convex forehead, with a protruding muzzle which forms a sort of beak; they have teeth in both jaws, numerous and conical, broad and high cranium, nasal pa.s.sages vertical, no caec.u.m. They are gregarious in habit, carnivorous and extremely swift, but they must not be confounded with the dolphin of sailors, which is a true fish (_Coryphaena hipparis_) of great velocity and brilliant colours, which change like rainbow tints when the fish is dying. I have several times in vain tried to catch the fleeting shades with both oil and water-colours, but without success; for within a few minutes they change from the most vivid of greens and blues to a pale silvery grey. The true dolphin, of which we are treating, is the dolphin of the ancients, represented in all the old pictures and sculptures. They have a medium dorsal fin, and the pectoral flippers are about two-thirds longer than the breadth.

[Ill.u.s.tration: 1. Gangetic Dolphin--_Platanista Gangetica_. 2.

Round-headed River Dolphin--_Orcella brevirostris_. 3. Gadamu Dolphin--_Delphinus Gadamu_. 4. Freckled Dolphin--_Delphinus lentiginosus_. 5. Black Dolphin--_Delphinus pomeegra_.]

NO. 260. DELPHINUS PERNIGER.

_The Black Dolphin_ (_Jerdon's No. 142_).

HABITAT.--Bay of Bengal.

DESCRIPTION.--"Twenty-six teeth on each side above and below, obtuse, slightly curved inwards; of a uniform shining black above, beneath blackish."--_Jerdon_.

SIZE.--Total length, 5 feet 4 inches.

This species was taken in the Bay of Bengal and sent to the Asiatic Society's Museum by Sir Walter Elliot, but it does not appear to be mentioned by Professor Owen in his notice of the Indian Cetacea collected by Sir Walter Elliot.

NO. 261. DELPHINUS PLUMBEUS.

_The Lead-coloured Dolphin_ (_Jerdon's No. 143_).

HABITAT.--Malabar coast.

DESCRIPTION.--Thirty-six teeth in each side in the upper jaw and thirty-two in the lower jaw; of a uniform leaden colour, with the lower jaw white.

SIZE.--About 8 feet.

Whether this be the same as or a different species to the next I am unable to say, as the description is meagre, and the number of teeth vary so much in the same species that no definite rule can be laid down on them.

The following are the species named by Professor Owen and collected by Sir Walter Elliot.