Popular Science Monthly/Volume 50/November 1896/The Abundance of Animal Life
|THE ABUNDANCE OF ANIMAL LIFE.|
WE find in studying the past epochs of the earth's history that they have been marked by an abundance of life, even exceeding any which prevails in the present. Comparing the existing state with the past, we are struck with the immensity of the part played by the inferior organisms. Life is everywhere; the number of microbes is infinite. Rocks which at first seem to belong only to the domain of mineralogy are found to appertain very largely to that of biology. One of the grandest spectacles, for example, is offered by the travertines of the Mammoth Hot Springs, in the Rocky Mountain National Park, which Mr. Weed declares are formed chiefly through the agency of algæ, withdrawing the excess of carbonic acid from the water, and forcing the precipitation of the limestone. Going from the hot springs to the geysers, we find deposits of silica which have been formed in the same way; and what is called gelatinous silica is largely vegetable matter. The lower animals are also so numerous in some places that they contribute to the formation of rocks. Plancus has calculated that three grammes of certain sands of the Caribbean Sea contain 180,000 shells of foraminifera. M. Schlumberger found 116,000 foraminifera shells in a cubic centimetre of the Atlantic mud which was brought up by the Travailleur expedition. Polyps construct atolls, barrier reefs, and islands; and if the bottoms of the oceans were uncovered we should doubtless see coralline rocks no less extended than the Secondary formation called the coral rag. It is said that the shells of the Etheria form such large beds in the Senegal that they are quarried to be made into lime, and that on the shores of Lake Pontchartrain, near New Orleans, the Gnathodons form a bed four miles and a half long, nearly two hundred feet wide, and sixteen feet thick. I have been informed by M. Sauvage, to whom we owe many important works on marine animals, that the year's crop of oysters as entered in the statistical tables of the Minister of the Marine reaches the prodigious figure of 1,407,390,400. In the same year there were returned 1,262,600 bushels of mussels and 620,000 bushels of other shellfish than oysters and mussels. The same authority estimates that 2,200,000 lobsters, 16,000,000,000 shrimps and prawns, 1,080,000,000 sardines, and 400,000,000 herrings are consumed in France in a single year. The cod, the mackerel, and the fresh fishes would also represent considerable quantities. The fishermen of the single port of Boulogne took 63,000,000 kilogrammes of fish during a period of nine years. Assuredly the statistics of such other countries as Great Britain, Norway, and Newfoundland would give not less considerable figures. These numbers illustrate the richness of the life that is concealed under the waves of existing seas.
Although the reptiles are much less various in our epoch than during the Secondary age, they are still numerous in some regions. According to Alcide d'Orbigny, caymans are numbered by thousands in the province of Moxos. The traveler Leguat, speaking of the extinct tortoises of the island of Rodriguez in 1708, wrote that they were seen sometimes in troops of two or three thousand, so that one could go more than two hundred paces on their backs without putting his foot on the ground. M. A. Milne-Edwards found reports in the office of the ministry according to which thirty thousand tortoises were taken from Rodriguez in a year and a half to supply Mauritius and Réunion. Venomous serpents are so common in India that M. Sauvage says that in comparison with them tigers and panthers are inoffensive beasts. According to official documents, more than nineteen thousand persons perished in India in one year from snake bites.
Warm-blooded animals have especially multiplied in our epoch. Livingstone met in the country of the Makololos more than thirty different species of birds; among them hundreds of ibis, files of three hundred pelicans, myriads of ducks, many geese, herons, kalas, crossbills, burgills, spoonbills, and flamingoes, and an enormous multitude of gulls and cranes. Delegorgue has also executed paintings showing the abundance of the birds. He speaks of having seen five hundred or a thousand vultures upon a single elephant's carcass. Nothing, he says, is more s range to the hunter than to see rising at his approach, circling in the air, that mass of feathered creatures which forms a kind of immense movable dais above him. Alcide d'Orbigny, in his travels in Bolivia, descending the Mamoré, found its banks animated with innumerable shore birds. The tantalus, in troops of several thousands, marched with slow steps upon the muddy parts in company with the red spoonbill or white egret, while the sand banks were covered with scissorbills and sea swallows, together with many goat-suckers. In the country of the Chiquitos, D'Orbigny met cardinal and cacique birds which "possessed the qualities rarely found together, of melodious song and brilliant plumage. Toucans made the woods resonant with their sharp accents, which were mingled with the disagreeable cries of paroquets of numerous species and of red and yellow aras. . . . The woods resounded with the cadenced cries of the penelope and the hoecos; by means of his cry at a fixed hour the kamichi serves the Indians instead of a clock."
The abundance of mammals is still more extraordinary than that of birds. Livingstone speaks of a band of more than ten thousand euchoris antelopes. Delegorgue says, describing a meeting he had with these animals: "The dust flew and formed thick clouds in a hundred directions. Sometimes it rose in whirling columns to the height of one hundred or two hundred feet. . . . Immediately I perceived the innumerable troops of springboks which were raising these clouds. . . . The vision astonished me so that I had to question myself in order to be sure that it was not a vision. There were bands of from three to ten thousand individuals each, crossing one another's course at all points at once." The same traveler speaks also of large herds of gnus and elands; and he speaks of bands of a thousand or fifteen hundred buffaloes.
Allen, in his admirable work on the bisons of America, gives some curious details on the importance their herds once had and on their extinction. The 2,500,000 bisons that were killed between 1870 and 1875 would represent 50,000,000 in a century.
The solipedes abound in our epoch. Delegorgue saw bands of four or five hundred quaggas in Africa. Mr. Blanford says that Dr. Aitchison met a troop of one thousandin Afghanistan. Brehm estimates, following Youatt, that the number of horses in all Russia is near 20,000,000 head. The rapidity with which horses left loose multiply in America is well known. Wild elephants are destined to be annihilated by man, but they are still numerous in some regions. Speke relates that when he was on the banks of the Nile, he found himself in the midst of a drove of several hundred elephants. Delegorgue estimates the number of elephants which he saw on a space about ten thousand feet in diameter in the Amazulu country at six hundred.
The rodents have a surprising force of propagation and multiply with the most astonishing rapidity. In 1863 a Mr. Austin took some rabbits to Australia for stocking his hunting grounds. The introduction of them was a disaster. They have so multiplied that thousands and thousands of acres of land have been ravaged, and thousands of men ruined. According to a report made three years ago, there are 20,000,000 rabbits in southern Victoria and northern Queensland. Brehm relates that 1,500,000 of field mice (Arvicola arvalis) were destroyed in fifteen days in the canton of Saverne, and that a factory in Breslau having offered a centime (a quarter of a cent) a dozen for these animals, some peasants delivered fourteen hundred of them a day. Charles Martens has given some curious details concerning the immense troop of lemmings (Myodes) in Norway. I was struck with the multitude of squirrels in the Rocky Mountains. We met them at every step in passing through the wooded regions. Alcide d'Orbigny relates that when at Carmen de Moxos he was nearly suffocated by the odor of musk in his house. It came from the thousands of bats that hung from the roof during the day. Marine mammals were also very numerous before they were pursued by man. Buffon says that in 1704 the crew of an English ship met a school of more than a thousand morses near Cherry Island, in latitude 75°.
Notwithstanding the number of beings that disappeared in the various geological epochs, I believe that the sum of the appearances surpassed that of the extinctions till the end of the Miocene. I can not assert that there has not been some diminution since that period; but we can affirm that a prodigious fecundity prevails at the present time.—Translated for the Popular Science Monthly from the Revue des Deux Mondes.