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By Phil Myers
Members of this family are the "flying foxes" and other fruit-eating bats of the Old World. The family includes around 166 living species placed in approximately 42 genera. Species of pteropodids can be found in tropical and subtropical regions of Africa, through southern and central Asia to Australia, including the Philippines and a number of Pacific islands. They are especially diverse in southeastern Asia, the Indonesian Archipelago, and Australia.
Some pteropodids are big. Members of the largest species of the family, in the genus Pteropus, approach a kilogram in weight and have a wingspan of up to 1.7 meters. Most species, however, are small to medium in size.
Pteropodids are distinguished from other bats by a combination of the following characteristics:
- the second finger is relatively independent of the third finger and usually retains a claw (absent in all other bat families);
postorbital processes of skull well developed;- bony palate elongated, extending well beyond the last upper molar;
- dental formula highly variable, but never more than 2 upper and 2 lower incisors on each side of the jaw, and the total number of teeth is usually small compared to microchiropterans;
- the premaxilla (the bone that bears the incisor teeth in the upper jaw) is well developed and lacks a palatal branch;
- ears are relatively simple, lacking specializations for echolocation (such as a tragus), and with a relatively small cochlea;
- the tail is usually small or absent; when present, it is not ensheathed in a tail membrane.
Many species are sexually dimorphic. Differences between the sexes include the larger body size of males (most species), males having larger canines (many species), and males with conspicuous skin glands (a few species). Sexual differences are extreme in one species, Hypsignathus monstrosus, in which males have very large pharangeal sacs that extend into the chest and a huge larynx (used in producing a loud "honk" that is part of a sexual display).
All pteropodids are frugivorous or nectarivorous. Their molar-like teeth are simple in structure and often reduced in size compared to those of other bats, a tendency that is carried to an extreme in nectar-feeding species.
Members of this family are usually strong fliers, but they lack the specializations of wings and shoulders seen in many other bat families, and their flight style is relatively simple.
Pteropodids also differ from other bats in that most use sight, rather than echolocation, as a means of navigation. Their eyes are large and they see very well. Echolocation is known in at least one pteropodid, but it differs in a number of ways from that of other bats and is probably independently evolved. Pteropodids also rely heavily on their sense of smell to help them locate fruit.
Pteropodids are important pollinators and dispersers of tropical trees, many of which are adapted to attract bats and make their pollination/dispersal activities more efficient. In some instances pteropodids may also cause significant damage to orchards. The larger species are sometimes hunted for their meat.
The fossil record of pteropodids extends to the middle Oligocene.
References and literature cited:
Feldhamer, G. A., L. C. Drickamer, S. H. Vessey, and J. F. Merritt. 1999. Mammalogy. Adaptation, Diversity, and Ecology. WCB McGraw-Hill, Boston. xii+563pp.
Hill, J. E., and J. D. Smith. 1984. Bats, a Natural History. University of Texas Press, Austin. 243 pp.
Koopman, K.F. 1984. Bats. Pp. 145-186 in Anderson, S. and J. K. Jones, Jr. (eds). Orders and Families of Recent Mammals of the World. John Wiley and Sons, N.Y. xii+686 pp.
Vaughan, T. A., J. M. Ryan, N. J. Czaplewski. 2000. Mammalogy. Fourth Edition. Saunders College Publishing, Philadelphia. vii+565pp.
Wilson, D. E., and D. M. Reeder. 1993. Mammal Species of the World, A Taxonomic and Geographic Reference. 2nd edition. Smithsonian Institution Press, Washington. xviii+1206 pp.
Contributors
Phil Myers (author), Museum of Zoology, University of Michigan.
