The American Crocodile
Of about a dozen existing species of crocodile, but one, the American crocodile, C. americanus, is found in the United States, and it is limited to the swamps and coast of southern Florida below Lake Worth; its greater sensitiveness to cold is doubtless the cause of its not being found so far north as the alligator. Its range extends south through Mexico and Central America into South America. It was first found in Florida by Dr. Hornaday in 1875. It sometimes reaches a length of fourteen feet.
As has already been noted there is, besides certain structural differences, a marked difference in the dispositions of the Florida alligator and crocodile. While an alligator may snap its jaws, hiss, and swing its tail from side to side, it is not difficult for a couple of men with ropes and a pole to safely tie up a large specimen. The struggles of a crocodile are of a more serious nature. Ditmars thus describes an encounter with a captive Florida crocodile: “The writer well remembers his first acquaintance with a big fellow from Florida. Driven out of the crate the crocodile looked the picture of good nature. Standing away from what he thought to be the reach of his tail, the writer prodded the apparently sluggish brute with a stick to start it for the tank. Several things happened in quick order. With a crescentic twist of the body utterly beyond the power of an alligator, the brute dashed its tail at the writer, landing him such a powerful blow that he was lifted completely from the ground. As he left terra firma, an almost involuntary inclination caused him to hurl his body away from a pair of widely-gaping, tooth-studded jaws swinging perilously near. Landing with a thud on one shoulder, though otherwise unhurt, the writer threw himself over and over, rolling from the dangerous brute that was actually pursuing him on the run, body raised high from the ground. For an instant it seemed as if the crocodile would win. As the writer sprang to his feet and glanced backward, he beheld the brute throw itself flat on its belly, open the jaws widely, then remain motionless as a statue. Such is the average crocodile—an active, vicious and, above all, treacherous brute.” Ditmars says again, in the same book: “When the keepers of the reptile house of the New York Zoölogical Park clean out the big pool of the crocodilians, they actually walk over the backs of some of the big ’gators, so tame are these. They never become unduly familiar with the crocodiles, finding it necessary to pen the latter behind heavily barred gates—and in the process the men are often chased from the enclosure.”
Nile Crocodile. (Crocodilus niloticus.)
Distribution: Africa generally; Madagascar.
Grows to a length of sixteen feet. (After Ditmars.)
(Reproduced by Permission of Sturgis & Walton Co.)
Fig. 11. West African Crocodile. (Crocodilus cataphractus.)
Distribution: West Africa.
Does not attain so large a size as the Nile Crocodile. (After Ditmars.)
(Reproduced by Permission of Sturgis & Walton Co.)
In contrast to this ferocious aggressiveness in captivity the American crocodile is said to be very timid and retiring when in its native habitat.
Young animals are greenish with black marking; as they become older they are of an olive color, and old specimens are dull gray.
The Orinoco Crocodile, C. intermedius
This is a species with a very narrow snout that is not quite so large as the preceding. It is said to be abundant in the Orinoco River and its tributaries.
Besides the two above mentioned there is a small species, C. rhombifera, found only in Cuba and hence known as the Cuban crocodile.
The African or Nile Crocodile, C. niloticus
This well known and much feared species is found throughout the continent of Africa, and is very common on the island of Madagascar ([Fig. 11]). In the lower waters of the Nile it is now nearly exterminated. It has always been a conspicuous animal in Egypt and was one of the animals held sacred by the Egyptians and preserved by them as mummies. It is discussed by Herodotus, and the “leviathan” mentioned in the Book of Job is doubtless this crocodile. In fact the name is said to be derived from the ancient Greek for lizard, just as the word alligator is said to be derived from the Spanish for lizard—el lagarto; the resemblance in form between these big saurians and their smaller relatives is evident. The alligator, being confined to America and a small part of Asia, was probably not known to the ancients.
An excellent account of the development and habits of the present species is given by Voeltzkow ([78]), who says it is, perhaps, the most common vertebrate in Madagascar. The largest specimen measured by this observer was thirteen feet; Ditmars gives sixteen feet as the maximum size. This man-eating crocodile, according to Ditmars, destroys more human lives than any other wild animal of the dark continent.
The story told by Herodotus of the bird, probably a species of plover, which enters the gaping mouth of the crocodile to pick off the leeches found there may be true, since there is such a bird that may be seen perching on the backs of crocodiles, and as the Crocodilia frequently lie with their mouths wide open it is quite possible that these birds may pick off the worms that are often found within. It is also possible that the alertness of these birds to danger may serve as a warning to the crocodiles with which they associate.
Fig. 12. Salt-Water Crocodile. (Crocodilus porosus.)
Distribution: India to North Australia. Occurs at sea.
Grows to a length of twenty feet. (After Ditmars.)
(Reproduced by Permission of Sturgis & Walton Co.)
According to Voeltzkow these crocodiles dig caves of thirty-nine to forty feet length in the banks of the streams they inhabit, into which they retire on the approach of danger. The caves open under water and slope upward towards the surface of the ground where a few small air-holes are found. The natives locate the caves by means of the air-holes and dig out the hidden animal, first stopping up the entrance.
In Madagascar the eggs are laid in August and September and hatch in about twelve weeks; they are laid at night, usually shortly before daybreak. From twenty to thirty eggs are laid in one nest, which is merely a hole dug in the dry sand. As was said in connection with the Florida alligator, the habits of the two animals are quite different in this respect,—the moisture that is so important in the one case is fatal to the embryo in the other. When the eggs are laid the nest is filled in with sand so that there is nothing to indicate its position except that the female crocodile is in the habit of lying on the spot where her eggs lie buried.
Like the alligator the young crocodile makes a squeaking noise shortly before hatching and the mother doubtless opens the nest, at this time, to allow the young to escape. A fence that Voeltzkow built around a nest was repeatedly broken down by the mother in attempting to get back to her eggs.
The character of the crocodile’s egg is discussed, in comparison with that of the Florida alligator, on [page 23].
The Marsh Crocodile or Mugger, C. palustris
Found in India, Ceylon, Burmah, the Malay Peninsula, and many of the islands in that region. It has a rather broad snout, and reaches a length of twelve feet. It is a timid form and is harmless to man. It is frequently venerated by the Hindoos and is kept in a semi-domesticated condition in ponds where it is fed and becomes very tame.
In the dry season when the natural ponds are empty they sometimes migrate overland in search of water, but generally they bury themselves in the mud and lie dormant until the rains begin again.
The Salt-Water Crocodile, C. porosus
This is one of the largest if not the largest of living reptiles ([Fig. 12]). It is said by Ditmars to reach a length of twenty feet and there is a record of one specimen that was thirty-three feet in length. It is said to be easily recognized by the prominent, longitudinal ridge that extends in front of each eye, over the prefrontal bone, and by the absence of the suboccipital scutes.
Fig. 13. Skull of Gavial.
(Dorsal View.)
(Photograph from U. S. National Museum.)
Fig. 14. Skull of Gavial.
(Lateral View.)
(Photograph from U. S. National Museum.)
It is typically an inhabitant of tidal waters and is sometimes found swimming at sea, out of sight of land; it seldom goes inland to any great distance from the sea. It is a man-eating species and many human lives are said to be destroyed by it in India and surrounding countries. A British “blue book” states that in British India 244 deaths were caused by Crocodilia in the year 1910.
In captivity it is savage and untamable. Ditmars, in speaking of three specimens that he had in captivity, says they were “positively the most vicious reptiles” he had ever seen.
The Indian Gavial, Gavialis gangeticus
This animal, which inhabits the Ganges and other rivers of northern India, is, with the possible exception of the preceding species, the largest of the Crocodilia; it is said to reach a length of thirty feet, which is twice that of a very large Florida alligator. As previously noted its snout is extremely long and narrow ([Figs. 13 and 14]), with a large, fleshy hump at the tip, that projects above the muddy water in which the animal lies concealed.
It is a timid animal and, in spite of its huge size, dashes quickly into the water on the approach of man, to whom it is seldom or never dangerous. Its Indian name, gharial, from which its generic name has been corrupted, means fish-eater, since its food consists, it is said, largely if not entirely of fish.
Considering its huge size and the character of its jaws and teeth as shown in [Figures 13 and 14], it is fortunate that it prefers fish to human flesh.
Anderson ([2]) describes the eggs and young of the Indian gavial. He found forty eggs in a nest of sand; they were in two layers, with a foot of sand between them. The young were 15.8 inches long at hatching. He says: “The young run with amazing rapidity the moment they are out of the shell.... Some of them actually bit my fingers before I had time to remove the shell from their bodies.” The following quotation from Oldenburg ([46]), for which I am indebted to Dr. Hussakof, is perhaps the earliest reference to the egg of the American alligator. It also mentions the habit that is practiced by some of the recent Crocodilia of swallowing stones to aid in digestion, as was apparently done by some of the large extinct reptiles.
“The eggs of Crocodiles and Alligators are little bigger than a Turkey’s. I thought to bring one to England, but it was lost. I never broke any to see the Yolk and White; but the Shell is as firme and like in shape to a Turkey’s, but not spotted. I inquired into the Stone in the Stomach of a Cayman or Crocodile, and I found by the inquiry of a very observing gentleman there, that they were nothing but several Stones, which that Creature swallows for digestion. He took out of one a piece of a Rock as big as his head: out of others he had taken sixteen or twenty lesser. None regards them much there, whatever Monardes relateth.”