Microbat


Microbats constitute the suborder Microchiroptera within the order Chiroptera (bats). Bats have long been differentiated into Megachiroptera (megabats) and Microchiroptera, based on their size, the use of echolocation by the Microchiroptera and other features; molecular evidence suggests a somewhat different subdivision, as the microbats have been shown to be a paraphyletic group.[1]

Microbats are 4 to 16 cm (1.6–6.3 in) long.[2] Most microbats feed on insects, but some of the larger species hunt birds, lizards, frogs, smaller bats or even fish. Only three species of microbat feed on the blood of large mammals or birds ("vampire bats"); these bats live in South and Central America.

Although most "Leaf-nose" microbats are fruit and nectar-eating, the name “leaf-nosed” isn't a designation meant to indicate the preferred diet among said variety.[3] Three species follow the bloom of columnar cacti in northwest Mexico and the Southwest United States northward in the northern spring and then the blooming agaves southward in the northern fall (autumn).[4] Other leaf-nosed bats, such as Vampyrum spectrum of South America, hunt a variety of prey such as lizards and birds. The horseshoe bats of Europe, as well as California leaf-nosed bats, have a very intricate leaf-nose for echolocation, and feed primarily on insects.

The form and function of microbat teeth differ as a result of the various diets these bats can have. Teeth are primarily designed to break down food; therefore, the shape of the teeth correlate to specific feeding behaviors.[5] In comparison to megabats which feed only on fruit and nectar, microbats illustrate a range of diets and have been classified as insectivores, carnivores, sanguinivores, frugivores, and nectarivores.[6] Differences seen between the size and function of the canines and molars among microbats in these groups vary as a result of this.

The diverse diets of microbats reflect having dentition, or cheek teeth, that display a morphology derived from dilambdodont teeth, which are characterized by a W-shaped ectoloph, or stylar shelf.[7] A W-shaped dilambdodont upper molar includes a metacone and paracone, which are located at the bottom of the “W”; while the rest of the “W” is formed by crests that run from the metacone and paracone to the cusps of the stylar self.

Microbats display differences between the size and shape of their canines and molars, in addition to having distinctive variations among their skull features that contribute to their ability to feed effectively. Frugivorous microbats have small stylar shelf areas, short molariform rows, and wide palates and faces. In addition to having wide faces, frugivorous microbats have short skulls, which place the teeth closer to the fulcrum of the jaw lever, allowing an increase in jaw strength.[8] Frugivorous microbats also possess a different pattern on their molars compared to carnivorous, insectivorous, nectarivorous, and sanguinivorous microbats.[6] In contrast, insectivorous microbats are characterized by having larger, but fewer teeth, long canines, and shortened third upper molars; while carnivorous microbats have large upper molars. Generally, microbats that are insectivores, carnivores, and frugivores have large teeth and small palates; however, the opposite is true for microbats that are nectarivores. Though differences exist between the palate and teeth sizes of microbats, the proportion of the sizes of these two structures are maintained among microbats of various sizes.[6]


The ventral view of microbat teeth
Ventral view of a free-tailed microbat (Genus Tadarida) skull displaying a dilambdodont teeth pattern. Specimen from the Pacific Lutheran University Natural History collection.
The frontal view of microbat teeth
Frontal view of a free-tailed microbat (Genus Tadarida) skull displaying the canine teeth. Specimen from the Pacific Lutheran University Natural History collection.
The skull of a microbat
Ventral view of a Florida Freetail bat (Tadarida cyanocephala) skull, highlighting both the stylohyal and tympanic bones. Specimen from the Pacific Lutheran University Natural History collection.
A series of Romanian postage stamps. The bats depicted are (from top to bottom and left to right): the greater mouse-eared bat, the lesser horseshoe bat, the brown long-eared bat, the common pipistrelle, the greater noctule bat, and the barbastelle, Romanian post miniature sheet, 2003