Thyroptera tricolor is one of two species in the family Thyropteridae, more commonly known as the Disc-winged Bats or New World Sucker-footed Bats. As the common names imply, these bats are easily recognizable by the presence of a circular sucking disk on the bases of the thumbs and soles of the feet. The suckers are used during roosting, when the bats hang head-up inside the tubular, young leaves of Heliconia trees. The suction created by the disks (and strengthened by licking and sweat gland secretions), is so powerful that only one sucker is needed to support a bat’s full weight (Nowak 1991). |
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This small species, with a body length of 34-52 mm and an average weight of just 4.2 grams, can be found in tropical forests from southern Mexico to Bolivia and South Brazil and also on the Island of Trinidad (Nowak 1991). While some members of this species elect to follow a solitary lifestyle, it is not uncommon to discover up to ten individuals roosting in the same Heliconia leaf and seeking out new habitat together when that leaf matures and opens. Like many species of bat, T. tricolor is insectivorous and can eat up to one-quarter of its body weight in prey during a single night’s activities.
In appearance, Thyropterids have long, slender snouts and large, funnel shaped ears. The snout lacks a noseleaf, and is instead covered with warts that may serve a sensory function. The nares are circular in shape and are spaced rather far apart from one another. The general head shape of Thyropteridae most closely resembles that of Natalids and Furipterids as all three share a considerably elevated crown and a concave forehead (Hill and Smith 1984).
Specific characteristics of the Thyropterid skull include the presence of a tragus, a relatively small auditory bullae that covers only a portion of the cochlea, and the lack of a postorbital process (Anderson and Jones 1984). Additionally Thyropterids have a complete premaxilla, well-developed premolars, and palatal branches that isolate two foramina (Anderson and Jones 1984). The overall dental formula is 2/3, 1/1, 3/3, 3/3 and gaps can be found separating the incisors and canines and the left and right incisors (Anderson and Jones 1984).
A large number of post-cranial characteristics also diagnose Thyropteridae and according to Anderson and Jones (1984) the list includes: toes with only two phalanges; second finger reduced to an incomplete metacarpal; third phalanx of third finger ossified; a small presternum with a forward facing keel, mesosternum with obsolete keel, and xiphisternum with reduced keel; separate lumbar vertebrae; first and second thoracic vertebrae fused; third and fourth toes fused through to the tips and claws; a reduced fibula; and a fused sacrum, with the last two vertebrae distinct. In males there are both a baculum and pubic symphysis present.
During scanning of the whole skeleton, it was discovered that this female specimen contained a single, well-developed embryo, which can be viewed on its own page here. Thyroptera tricolor breeds twice annually and mating is known to be polygonous. The young are unable to fly for the first month and so after birth the mother will carry her single offspring in flight, with the baby clinging to her abdomen (Anderson and Jones 1984).
Literature
Anderson, S. and J. K. Jones, Jr. 1984. Orders and Families of Recent Mammals of the World. John Wiley and Sons, New York. 686pp.
Hill, J. E. and J. D. Smith. 1992. Bats: A Natural History . University of Texas Press, Austin. 243pp.
Nowak, R. 1991. Walker's Mammals of the World, 5th edition. The John's Hopkins University Press, Baltimore and London. 642pp.
Links
Thyroptera tricolor on Animal Diversity Web (The University of Michigan).
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