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Hot spots cool and heat: Brazilian free-tailed bat


Vasculature of thermal hotspots / Jonathan Rei.. / LicenseCC-by-nc-nd - Attribution Non-commercial No Derivatives

The flanks of Brazilian free-tailed bats aid thermoregulation due to a unique arrangement of arteries and veins creating thermal windows.

"The Brazilian free-tailed bat (Tadarida brasiliensis) experiences challenging thermal conditions while roosting in hot caves, flying during warm daylight conditions, and foraging at cool high altitudes. Using thermal infrared cameras, we identified hot spots along the flanks of free-ranging Brazilian free-tailed bats, ventral to the extended wings. These hot spots are absent in syntopic cave myotis (Myotis velifer), a species that forages over relatively short distances, and does not engage in long-distance migration. We hypothesized that the hot spots, or 'radiators,' on Brazilian free-tailed bats may be adaptations for migration, particularly in this long-distance, high-flying species. We examined the vasculature of radiators on Brazilian free-tailed bats with transillumination to characterize the unique arrangements of arteries and veins that are positioned perpendicular to the body in the proximal region of the wing. We hypothesized that these radiators aid in maintaining heat balance by flushing the uninsulated thermal window with warm blood, thereby dissipating heat while bats are flying under warm conditions, but shunting blood away and conserving heat when they are flying in cooler air at high altitudes. We also examined fluid-preserved specimens representing 122 species from 15 of 18 chiropteran families and radiators appeared present only in species in the family Molossidae, including both sedentary and migratory species and subspecies. Thus, the radiator appears to be a unique trait that may facilitate energy balance and water balance during sustained dispersal, foraging, and long-distance migration." (Reichard et al. 2010:358)
About the inspiring organism
Med_bats3a_sized Brazilian free-tailed bat
Tadarida brasiliensis (I. Geoffroy, 1824)
Common name: Brazilian free-tailed bat

Learn more at
Some organism data provided by: ITIS: The Integrated Taxonomic Information System
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Bioinspired products and application ideas

Application Ideas: Creating "vascularized hot spots" on buildings, computers, clothing, sleeping bags, etc.

Industrial Sector(s) interested in this strategy: Architecture, computer engineering, manufacturing

Kunz Bat Lab, Center for Ecology and Conservation Biology
Thomas H. Kunz Jonathan D. Reichard
Department of Biology, Boston University
Reichard JD; Prajapati SI; Austad SN; Keller C; Kunz TH. 2010. Thermal windows on Brazilian free-tailed bats facilitate thermoregulation during prolonged flight. Integrative and Comparative Biology. 50(3): 358-370.
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Reichard JD; Fellows SR; Frank AJ; Kunz TH. 2010. Thermoregulation during flight: body temperature and sensible heat transfer in free-ranging Brazilian free-tailed Bats (Tadarida brasiliensis). Physiological and Biochemical Zoology. 83(6): 885-897.
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