Emballonuridaesac-winged bats, sheath-tailed bats, and relatives

Em­bal­lonurids are known as sac-winged or sheath-tailed bats. The first of these names de­scribes the glan­du­lar sac usu­ally found on the propatag­ium (lead­ing edge of the wing) in many species. This gland pro­duces a scent used in so­cial dis­plays and to mark ter­ri­to­ries. Males of some species have a pouch at the base of the throat that may serve a sim­i­lar func­tion. Em­bal­lonurids are also known as sheath-tailed bats be­cause their tail ap­pears to be sheathed in a mem­brane (uropatag­ium or in­ter­femoral mem­brane). The tip of the tail pro­trudes from the top of this mem­brane and does not ex­tend for the full length of the mem­brane.

This fam­ily in­cludes 13 gen­era and 47 species. Their range is trop­i­cal and sub­trop­i­cal in both the Old and the New World.

Most em­bal­lonurid are brown or grey in color, but this fam­ily also in­cludes the whitish ghost bats ( Di­clidu­rus) and bats with a pair of white stripes down the back ( Sac­copteryx). Bats of this fam­ily are small to medium sized (5 to 105 g) and have a smooth face and lips, lack­ing the nose­leafs or nose or­na­ments found in some other bat fam­i­lies. Em­bal­lonurid ears are usu­ally sim­ple, round, and cup-shaped. They are often united by a band of skin across the fore­head, and a tra­gus is pre­sent (a fleshy lobe that pro­trudes from the ear).

The muz­zle of em­bal­lonurids is usu­ally short and broad, and there are in­flated si­nuses in the max­il­lae. of the ros­trum. Other skull char­ac­ters used to dis­tin­guish this fam­ily are the fol­low­ing: the pres­ence of a pos­tor­bital process (often well de­vel­oped); small pre­max­il­lae that lack palatal branches and that are not fused to each other or to the ad­ja­cent max­il­lae; and a palate that ends be­yond the plane of the last mo­lars.

Em­bal­lonurids have 30 to 34 teeth: 1-2 upper in­cisors, 2-3 lower in­cisors, 1 upper and 1 lower ca­nine, 2 upper and 2 lower pre­mo­lars, and 3 upper and lower mo­lars. The cheek teeth have a W pat­tern of cusps and ridges ( dil­amb­dadont), which is good for break­ing up the in­sects they eat. These bats are pri­mar­ily in­sec­tiv­o­rous (al­though they have been ob­served to eat fruit on oc­ca­sion) and hawk in­sects in flight. Their long nar­row wings allow them fast flight but make them some­what less ma­neu­ver­able than bats of some other fam­i­lies that char­ac­ter­is­ti­cally have broader wings. The 2nd fin­ger has no pha­langes, and the third has only 2.

Like all mi­crochi­ropter­ans, em­bal­lonurids use echolo­ca­tion to lo­cate prey. In­ter­est­ingly, there is also some ev­i­dence that bats in this fam­ily may use echolo­ca­tion for com­mu­ni­ca­tion.

Em­bal­lonurid bats shel­ter in rocky crevices, caves, ruins, houses, trees, leaves, and hol­low logs; their roosts tend to be more ex­posed than those found in some other bat fam­i­lies. Some em­bal­lonurids live in sta­ble year-round harems of 1-8 fe­males in a ter­ri­tory pa­trolled by the male. This mat­ing sys­tem is known as re­source de­fense polyg­yny. Other mem­bers of this fam­ily are soli­tary or colo­nial. Colonies of Coelura afra in­clude up to 50,000 bats, each of which re­turns to a pre­cise place in a roost­ing cave along the Kenyan coast.

The fos­sil record of em­bal­lonurids ex­tends to the late Eocene or early Oligocene.

Tech­ni­cal char­ac­ters

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.

An­der­son, S. and J. K. Jones, Jr., 1984. Or­ders and Fam­i­lies of Re­cent Mam­mals of the World. John Wiley and Sons, New York. 686pp.

Fen­ton, M. B., P. Racey, and J.M. V. Rayner (eds.), 1987. Re­cent Ad­vances in the Study of Bats . Cam­bridge Uni­ver­sity Press, Cam­bridge.

Hill, J. E. and J. D. Smith, 1992. Bats: A Nat­ural His­tory . Uni­ver­sity of Texas Press, Austin.

Nowak, Ronald M., 1994. Walker's Bats of the World . Johns Hop­kins Uni­ver­sity Press, Bal­ti­more.

Ran­some, Roger, 1990. The Nat­ural His­tory of Hi­ber­nat­ing Bats . Christo­pher Helm, Lon­don.

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

Lau­rel Hes­ter (au­thor), Phil Myers (au­thor), Mu­seum of Zo­ol­ogy, Uni­ver­sity of Michi­gan-Ann Arbor.

Glossary

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

motile

having the capacity to move from one place to another.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate