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Bats

( Originally Published 1936 )

THE second order of mammals includes the Bats, or Chiroptera, literally hand-winged animals, of which it is estimated that there are between four and five hundred species. They have four limbs and a tail, the fingers of the front limbs being enormously lengthened and used as a sup-port for the skin-like membranes serving as true wings, from which project the short thumbs armed with strong hooked claws which are used in climbing. The hind limbs are small and weak, and are connected with the tail by a membrane, the feet, how-ever, remaining free from it. As in the Primates, in which order the Bats were formerly included, there are four kinds of teeth, incisors, canines, premolars, and molars, the milk-set being followed by the permanent. The teeth are much modified in the different families and serve to distinguish them from each other. They are night animals, becoming active at twilight, sleeping during the day and hanging head downwards by the claws of their hind feet from the branches of trees, ruins, and various places of concealments. Some Bats feed entirely upon fruit, some upon insects, and a few suck the blood of other animals. Certain species that inhabit cold climates hibernate, like other animals that would find it difficult, or even impossible, to obtain food during this time of the year.

Four of the principal families are figured here.

Many species are known in this country. The commonest form in the eastern parts of the United States is the Red Bat (Atalpha noveboracensis), the species usually seen flying about at night and which frequently enters houses, not, as many people suppose, attracted by the lights, but by the various small insects that the lights draw. There is a common belief that Bats, when disturbed, will fly at once for a person's head, grasping the hair with their claws and refusing to be dislodged. Should one of these little creatures be so unfortunate as to come in contact with one's head in its efforts to escape, it would hold on tenaciously, but it does not by any means single out the head as the object of attack, endeavouring, rather, to avoid all obstacles. The mouth of the Red Bat is comparatively large and filled with strong sharp teeth, and the bite is rather severe.

Kalong (Pteropus edulis)

The Pteropid, or fruit-eating Bats, commonly called " flying-foxes " are confined to the tropical regions of the Old World, and differ from other families in several important characters. The muzzle is long and pointed, resembling that of a fox, the ear is small, having no tragus, or inner ear, and the margin forms a complete ring, no part of the margin being attached to the head ; the second finger usually has a claw at the end. The fur is a lighter or darker red, some specimens being almost black, and the neck is clothed with thick hair. See Plate 5, Fig. 20. The species figured is the largest known. measuring at least a foot in length and four or five feet between the tips of the wings. During the day these Bats hang head downwards from trees, wrapped in their wings to keep the light from their eyes, scattering in the evening to their feeding-grounds. They are extremely voracious, doing much injury to fruit plantations. The Kalong, and probably other allied species, are eaten by the natives of some of the countries in which they are found.

In all the following families of Bats the margin of the ear is attached to the head at its lower extremity.

Greater Horseshoe Bat (Rhinolophus ferrumequinum)

The Rhinolophidae, or Horseshoe Bats, are so called from the presence of a series of nose-leaves, the first of which is generally shaped like a horse-shoe, spreading out around the nostrils. Back of this is a central ridge, and behind it another leaf-like membrane, pointed in shape. Like the preceding family, these Bats are found only in the Old World, where they are widely distributed. In colour it is reddish-brown above, tinged with grey, and pale grey on the under part of the body. The ears are large, the tail rather short and contained entirely within the wing membrane. See Plate 5, Fig. 22. Hiding during the day in caves and ruins, these Bats come out rather late in the evening, flying about trees and feeding upon various insects, upon which they live exclusively. They are small, measuring rather less than two and a half inches, but the wings expand about a foot.

A still smaller and browner species, the Lesser Horseshoe Bat (Rhinolophus hipposiderus) is found in the south of England and Ireland, and extends farther north on the Continent of Europe than the larger species.

Long-Eared Bat (Plecotus auritus)

This species and the following represent the most typical family of Bats, the Vespertilionidae, which are found in both the Old World and the New. They differ from the preceding in being without the nose-leaf, and in having extremely long and delicate ears which may be wrinkled or folded back, leaving the tragus, or inner ear, standing. The Long-Eared Bat measures four inches in length, including the tail (which is almost entirely included in the membrane) and the wings expand at least thirteen or fourteen inches. The fur, which is very soft, is grey or brown above, but the base of the hairs is black. See Plate 5, Fig. 23.

Mouse-Coloured Bat (Vespertilio murinus)

This is the largest of the Central European Bats, measuring two and a half inches in length without the tail, which is somewhat shorter than the body. It is a representative of the Short-Eared Bats, which are more numerous in species than the genera previously noticed. The present species, however, which is greyish or reddish-brown above, with the base of the hairs black, and yellowish-white beneath, is very rare in England, though abundant on the Continent, where it lives in church towers, vaults, and ruins. Unlike other species it is not found in hollow trees. See Plate 5, Fig. 24. This Bat is also found in Northern Africa, and in Western and Central Asia. These bats hibernate, but are seen earlier in the spring and later in the autumn than the Long-eared Bats.

Vampire Bat (Vampyrus spectrum)

The large family of Phyllostomidae, or Vampire Bats, is confined exclusively to South America and the West Indies. In all the species the middle finger of the wing is three-jointed, and there is present either a well-marked nose-leaf or folds of skin on the chin. The one figured is the largest, being about six inches long, the wings expanding to two feet or more, and is brownish-grey in colour. See Plate 5, Fig. 21. In spite of its evil reputation and hideous aspect, this particular Bat is absolutely harmless, and so far as is known feeds entirely on fruit and insects.

There are, however, one or two species of the family Phyllostomidae that are blood-suckers, and in these the incisor teeth are curiously modified, being pointed, and set close together. When the Vampire alights on the shoulders or back of a horse, a favourite animal to attack, the sharp teeth pierce the skin and the blood is then drawn out by a peculiar sucking motion of the lips. The interior anatomy is specially adapted in order to enable the animal to digest this rather unusual food. For many years it was not definitely known whether this creature existed or not, but Charles Darwin actually saw one engaged in this operation of blood-sucking, and Theodore Gill, the American naturalist, was fortunate enough to witness the same performance while on an expedition in Chili.



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