Chapter One

Bats are members of the order Chiroptera, a Greek word meaning "hand wing". The order is divided into two suborders, Megachiroptera and Microchiroptera. Bat biologists, however, commonly shorten these names to megabats and microbats. Only one family of bats, Pteropodidae, comprises the suborder Megachiroptera, with all other families found in the suborder Microchiroptera. This nomenclature can be confusing because some of the megabats are smaller than some of the microbats.

Bats are the only true flying mammals. Their adaptations for flight, and their ability to navigate with echolocation (biosonar), have resulted in their unique appearance. The bat's wing (FIG. 1) is a modified hand, comparable to the arm and hand of a human; flight is made possible by a flexible membrane of skin stretched around and between the skeletal framework. The thumb is short, free, and possesses a claw that helps the bat cling to surfaces such as trees and walls. The other four digits have lost their claws and only serve to give rigidity to the flight apparatus.

Figure 1.  Structure of a bat wing.

Bats, like most other mammals, have fur or hair, give birth to live young, and feed their infants milk. The baby bat's first set of teeth are the milk teeth (FIG. 2), used for clinging to its mother's teat or fur while she carries it in flight. The milk teeth are tiny and sharply pointed. They erupt in the bat's mouth either prior to, or shortly after birth. As the infant bat matures, they are replaced by permanent teeth (FIG. 3). These teeth are differentiated and include incisors, canines, premolars and molars. All except the molars are deciduous (replaced once).

Figure 2.  Illustration of infant bat milk teeth  (from Kowalski, 1995

Figure 3.  Illustration of deciduous teeth of bats (from            Kowalski, 1955).

bats, they bounce off of surrounding objects and return as echos to the bats' ears (FIG. 4). Those species that have the ability to echolocate, can avoid dangerous obstacles and hunt insects even in total darkness. In addition to producing ultrasonic sounds, these animals also produce lower-frequency vocalizations that are within the range of human hearing. These sounds are associated with social interaction, however, and not navigation in flight.

Figure 4.  To hunt prey, bats emit ultrasonic sounds which are reflected by surrounding objects.  The sounds return to the bat as echos.

Among the Microchiroptera, temperate-zone bats are heterothermic. That is to say, these bats vary between acting like an ectotherm ("cold-blooded" animal) and an endotherm ("warm-blooded" animal). To conserve energy, heterothermic bats allow their body temperatures to decrease to ambient temperatures when at rest. When they awaken from torpor, they are able to raise their body temperatures again in order to fly and hunt. In contrast to this interesting thermoregulatory behavior, members of the order Megachiroptera (flying foxes) are like other mammals, obligatory endotherms; they maintain a constant body temperature through homeostatic mechanisms.

Collectively, bats eat a wide variety of foods. In addition to insects, they eat fruit, nectar, pollen, flowers, blood, mice, lizards, frogs, fish, birds, and even other bats. They also differ widely in physical appearance. Some bats have plain faces resembling dogs (FIG. 5), while others are elaborately adorned with leaflike structures (FIG. 6); moreover, the sizes and shapes of their ears are equally diverse. Bats exhibit different social behavior; while some species are solitary, others form enormous social groups. Perhaps one of the most amazing features about these small mammals is their incredible longevity. Representative longevity records are summarized in TABLE 1.

Figure 5.  This flying fox, and many other bats, have plain faces.	Figure 6.  Some bats have faces adorned elaborately with leaflike structures.

Worldwide, a wide variety of animals prey on bats, including predatory birds, snakes, lizards, large frogs, spiders, and mammals. Nevertheless, the predatory activities of all these animals combined do not have a significant effect on bat populations. Rather, it is the limitless global expansion of humans, with their ignorance, superstition, fear and greed, that threaten the very existence not only of bats, but all life.

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Bats In Captivity was adapted for the web
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