Animal Diversity Web

Di­ver­sity

Eurasian or Ukrain­ian blind mole-rats, the Spalacinae, com­prise a rel­a­tively small sub­fam­ily of Old-World fos­so­r­ial muroid ro­dents. There are 13 species in 1 genus, Spalax. (Musser and Car­leton, 2005)

Ge­o­graphic Range

The range of Spalacinae ex­tends around the east­ern por­tion of the Mediter­ranean and the Black Sea, from the Balkans through Ukraine, Asia Minor, Syria, Pales­tine, and into Egypt and Libya. (Car­leton and Musser, 1984; Nowak, 1999)

• Biogeographic Regions
• palearctic
  • native

Habi­tat

Spalacines live in mod­er­ately dense sandy or loamy soils that re­ceive more than 100 mm of an­nual rain­fall. They range from below sea level to above 2,600 me­ters, and they in­habit up­land steppes, moun­tain val­leys, agri­cul­tural fields, or­chards, wood­lands, river and lake basins, grass­lands, and brushy areas. (Car­leton and Musser, 1984; Nowak, 1999)

• Habitat Regions
• temperate
• terrestrial

• Terrestrial Biomes
• savanna or grassland
• chaparral
• forest
• scrub forest

• Other Habitat Features
• agricultural
• riparian

Phys­i­cal De­scrip­tion

Spalacines are chunky, mole­like an­i­mals with short legs, small feet and claws, sub­cu­ta­neous eyes, and ex­ter­nal ears that have been re­duced to tiny ridges. They range in length from 130 to 350 mm, and weigh 100 to 570 grams. There is no vis­i­bile tail. Mole rats have thick, soft fur that is nearly re­versible, al­low­ing the an­i­mals to eas­ily back down tun­nels. They have broad, cush­ioned snouts with which they pack earth into the walls of their bur­rows. There are stiff rows of tac­tile bris­tles run­ning down ei­ther side of a mole rat's face. The fur color is brown, red­dish, or yel­low­ish gray, and the ven­tral parts are gen­er­ally gray­ish or straw-brown. The front of a mole rat's head is paler than the rest of the body. The feet have a sil­very sheen to them, and there are five dig­its on each foot.

The spalacine den­tal for­mula is 1/1, 0/0, 0/0, 3/3 = 16. The broad in­cisors are or­tho­dont and pro­ject for­ward in front of the lips. The cylin­dri­cal cheek­teeth are rooted and have an enamel pat­tern in the shape of a Z or an S. The rows of mo­lars con­verge slightly pos­te­ri­orly. The first two mo­lars are about equal in size, and the third is slightly smaller. The jaw mus­cles, on which mole rats rely for dig­ging, are ex­tremely strong. Mole rats have heavy skulls and a wide ros­trum, but the zy­go­matic arches are quite thin and del­i­cate. The frontals are small and there are no supra­or­bital ridges. Adults usu­ally have a sagit­tal crest. The thick-walled au­di­tory bul­lae are some­what in­flated. Spalacines have 13 tho­racic ver­te­brae and six lum­bar ver­te­brae. The spalacine stom­ach is two-cham­bered and the cecum is di­vided into 18 to 20 cham­bers. There is no stape­dial artery; rather, the in­fra­or­bital artery pro­vides cir­cu­la­tion to the or­bits. Mole rats have a diploid chro­mo­some num­ber rang­ing from 38 to 62. (Car­leton and Musser, 1984; Nowak, 1999)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

Re­pro­duc­tion

Dur­ing the mat­ing sea­son, sev­eral males con­struct pe­riph­eral mounds around each fe­male's breed­ing mound, and mat­ing takes place within the breed­ing mound. Mole rats have elab­o­rate courtship rit­u­als. When a male and fe­male en­counter one an­other, they each as­sume a de­fen­sive pos­ture and make a se­ries of rushes at the other, at­tack­ing and then quickly re­treat­ing. The male emits a low-pitched growl, while the fe­male gives a high-pitched cry. Then, if both an­i­mals are ready to mate, they begin lick­ing and stroking one an­other, giv­ing off soft trills. Fi­nally, the male mounts the fe­male from be­hind, and cop­u­la­tion be­gins. Cop­u­la­tion can last up to 90 min­utes. How­ever, when cop­u­la­tion is fin­ished, the an­i­mals go their sep­a­rate ways; spalacines are promis­cu­ous and do not as­so­ci­ate with the op­po­site sex for long. (Car­leton and Musser, 1984; Har­ri­son, 1972; Nowak, 1999)

• Mating System
• polygynandrous (promiscuous)

Mole rats usu­ally breed just once a year, from No­vem­ber to March, and have their lit­ters from Jan­u­ary to April. Fe­male mole rats breed for the first time when they are about two years old, and most fe­males only have a sin­gle lit­ter in their life­time. Some do not breed at all. For those that do re­pro­duce, ges­ta­tion is about a month long. The lit­ter size ranges from one to six, but is usu­ally be­tween two and four. The young grow fur when they are about two weeks old and leave their mother's nest at about four to six weeks. (Car­leton and Musser, 1984; Nevo, 1999; Nowak, 1999)

• Key Reproductive Features
• semelparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
• viviparous

Fe­male mole rats build breed­ing mounds in which they mate and rear their young. Each mound can be up to 160 cm long by 135 cm wide and 40 cm high. Each has a nest cham­ber in the cen­ter. In­side, the fe­male nurses her al­tri­cial young for about a month. Other than pro­vid­ing sperm, male mole rats make no in­vest­ment in their off­spring. (Car­leton and Musser, 1984; Nowak, 1999)

• Parental Investment
• altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Lifes­pan/Longevity

Spalacines have a max­i­mum lifes­pan of four and half years in the wild, and an av­er­age lifes­pan of about three years. In cap­tiv­ity, mole rats have been known to live as long as 15 years. (Nevo, 1999; Nowak, 1999)

Be­hav­ior

Spalacines dig with their chisel-like in­cisors, push­ing and pack­ing earth with their broad snouts and kick­ing dirt out be­hind them with their hind feet. They build elab­o­rate bur­row sys­tems with two lev­els of pas­sage­ways: a top level for for­ag­ing, and and deeper level for liv­ing quar­ters. The top level pas­sage­ways run 10 to 25 cm below the soil sur­face and can stretch for hun­dreds of me­ters. As mole rats dig these for­ag­ing tun­nels, they push up mounds of earth that can stretch 500 cm wide. Mole rats also some­times in­cor­po­rate above-ground rest­ing mounds into their bur­row sys­tems that con­nect to their for­ag­ing tun­nels. The deeper pas­sage­ways in­clude one or two nest cham­bers, each about 20 to 30 cm wide and lined with plant ma­te­r­ial for bed­ding, and mul­ti­ple cham­bers for food stor­age and ex­cre­tion. These deeper cham­bers are usu­ally 20 to 50 cm below the soil sur­face. How­ever, mole rats dig even deeper dur­ing the hottest months of the year, when they are less ac­tive--they have been recorded as far 410 cm below the soil sur­face. Each mole rat bur­row sys­tem dis­places up to three tons of soil.

Mole rats are ac­tive at vary­ing times of the day or night; they some­times come above ground to for­age under the cover of dark­ness. They are soli­tary, ter­ri­to­r­ial, and ag­gres­sive to­wards in­trud­ers. The size of each mole rat's ter­ri­tory varies with the species, pop­u­la­tion, habi­tat, age, and sex. Pop­u­la­tion den­si­ties range from 0.1 to 23 mole rats per hectare. Most in­di­vid­u­als in any given mole rat pop­u­la­tion are adults, and the sex ratio is skewed to­wards fe­males. (Car­leton and Musser, 1984; Nevo, 1999; Nowak, 1999)

• Key Behaviors
• fossorial
• diurnal
• nocturnal
• motile
• sedentary
• solitary
• territorial

Com­mu­ni­ca­tion and Per­cep­tion

Mole rats nav­i­gate their pitch-black sub­ter­ranean en­vi­ron­ment by touch, and they also have acute hear­ing. Their mid­dle ears are spe­cially adapted to per­ceive low-fre­quency sounds, which travel well un­der­ground. Their sense of smell is thought to be rel­a­tively weak, but they do use pheromones to com­mu­ni­cate and they can sniff out their food. They make a va­ri­ety of grunt­ing and hiss­ing noises, es­pe­cially when threat­ened. They lo­cate one an­other dur­ing the mat­ing sea­son by rapidly drum­ming their heads against the ceil­ings of their bur­rows, cre­at­ing seis­mic vi­bra­tions. (Nevo, 1999; Nowak, 1999)

• Communication Channels
• acoustic
• chemical

• Other Communication Modes
• pheromones
• vibrations

• Perception Channels
• tactile
• acoustic
• vibrations
• chemical

Food Habits

Spalacines are her­bi­vores that eat mainly roots, bulbs and tu­bers. When they for­age on the sur­face from time to time, they con­sume grasses, seeds, stems, acorns, and a few in­sects. They store large amounts of plant ma­te­r­ial in their un­der­ground cham­bers. (Car­leton and Musser, 1984; Nowak, 1999)

• Primary Diet
• carnivore
  • insectivore
• herbivore
  • folivore
  • granivore

• Foraging Behavior
• stores or caches food

Pre­da­tion

Owls are the most im­por­tant preda­tors on mole rats. To avoid pre­da­tion, mole rats spend most of their time un­der­ground, and they can be ag­gres­sive when cor­nered. Also, their fur color is often cor­re­lated with soil color: mole rats in darker soils have darker fur, those in lighter soils have lighter fur. This sug­gests that vi­sual preda­tors exert a fair de­gree of se­lec­tive pres­sure on mole rat pop­u­la­tions. (Car­leton and Musser, 1984; Nevo, 1999; Nowak, 1999)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • owls (Strigiformes)

Ecosys­tem Roles

Mole rats prob­a­bly help to aer­ate the soil with their ex­ten­sive dig­ging ac­tiv­ity, and they are con­sumers of var­i­ous plant species as well as prey for owls.

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

There are no known pos­i­tive im­pacts of spalacines on hu­mans, ex­cept in their roles in healthy ecosys­tems they in­habit.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Spalacines can be­come se­ri­ous agri­cul­tural pests. (Car­leton and Musser, 1984; Nowak, 1999)

• Negative Impacts
• crop pest

Con­ser­va­tion Sta­tus

The IUCN cur­rently lists five of the 13 species in this fam­ily as vul­ner­a­ble: sandy blind mole rats (Spalax are­nar­ius), giant blind mole rats (or Russ­ian blind mole rats, Spalax gi­gan­teus), Balkan blind mole rats (or Bukovin blind mole rats, Spalax grae­cus), greater blind mole rats (Spalax mi­croph­thal­mus), and lesser blind mole rats (Spalax leu­codon). (IUCN, 2004)

• IUCN Red List [Link]

  Not Evaluated

Other Com­ments

The ear­li­est known spalacine fos­sil is about 25 mil­lion years old, from the lower Miocene of Greece. This makes Spalacinae the old­est sub­fam­ily within Spalacidae, at least in the fos­sil record. Mol­e­c­u­lar work is needed to clar­ify the di­ver­gence times be­tween spalacines and other spalacid groups. The ear­li­est known Spalax fos­sils are from the late Pliocene. Spalax arose in Eura­sia, and did not col­o­nize North Africa until the Pleis­tocene, be­tween 70,000 and 35,000 years ago. (Nevo, 1999; Savic and Nevo, 1990)

Con­trib­u­tors

Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Al­li­son Poor (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Al­ston, E. 1876. On the clas­si­fi­ca­tion of the order Glires. Pro­ceed­ings of the Zo­o­log­i­cal So­ci­ety of Lon­don: 61-98.

Car­leton, M., G. Musser. 1984. Muroid ro­dents. Pp. 289-379 in S An­der­son, J Jones Jr., eds. Or­ders and Fam­i­lies of Re­cent Mam­mals of the World. New York: John Wiley and Sons.

Cha­line, J., P. Mein, F. Pet­ter. 1977. Les grandes lignes d'une clas­si­fi­ca­tion évo­lu­tive des Muroidea. Mam­malia, 41: 245-252.

Eller­man, J. 1940. The Fam­i­lies and Gen­era of Liv­ing Ro­dents, vol. I. Lon­don: British Mu­seum (Nat­ural His­tory).

Har­ri­son, D. 1972. The Mam­mals of Ara­bia, vol. 3. Lon­don: Ernest Benn Ltd..

IUCN, 2004. "2004 IUCN Red List of Threat­ened Species" (On-line). Ac­cessed May 26, 2005 at www.​redlist.​org.

Jansa, S., M. Wek­sler. 2004. Phy­logeny of muroid ro­dents: re­la­tion­ships within and among major lin­eages as de­ter­mined by IRBP gene se­quences. Mol­e­c­u­lar Phy­lo­ge­net­ics and Evo­lu­tion, 31: 256-276.

Michaux, J., A. Reyes, F. Catze­flis. 2001. Evo­lu­tion­ary his­tory of the most spe­ciose mam­mals: Mol­e­c­u­lar phy­logeny of muroid ro­dents. Mol­e­c­u­lar Bi­ol­ogy and Evo­lu­tion, 18(11): 2017-2031.

Miller, G., J. Gi­d­ley. 1918. Syn­op­sis of su­per­generic groups of ro­dents. Jour­nal of the Wash­ing­ton Acad­emy of Sci­ence, 8: 431-448.

Musser, G., M. Car­leton. 1993. Fam­ily Muri­dae. Pp. 501-753 in D Wil­son, D Reeder, eds. Mam­mal Species of the World. Wash­ing­ton, D.C.: Smith­son­ian In­sti­tu­tion Press.

Musser, G., M. Car­leton. 2005. Su­per­fam­ily Muroidea. D Wil­son, D Reeder, eds. Mam­mal Species of the World. Wash­ing­ton, D.C.: Smith­son­ian In­sti­tu­tion Press.

Nevo, E. 1999. Mo­saic Evo­lu­tion of Sub­ter­ranean Mam­mals. Ox­ford: Ox­ford Uni­ver­sity Press.

Nor­ris, R., K. Zhou, C. Zhou, G. Yang, C. Kil­patrick, R. Hon­ey­cutt. 2004. The phy­lo­ge­netic po­si­tion of the zokors (Myospalacinae) and com­ments on the fam­i­lies of muroids (Ro­den­tia). Mol­e­c­u­lar Phy­lo­ge­net­ics and Evo­lu­tion, 31: 972-978.

Nowak, R. 1999. Walker's Mam­mals of the World, vol. 2. Bal­ti­more and Lon­don: The Johns Hop­kins Uni­ver­sity Press.

Savic, I., E. Nevo. 1990. The Spalacidae: evo­lu­tion­ary his­tory, spe­ci­a­tion and pop­u­la­tion bi­ol­ogy. Pp. 129-153 in E Nevo, A Reig, eds. Evo­lu­tion of Sub­ter­ranean Mam­mals at the Or­gan­is­mal and Mol­e­c­u­lar Lev­els. New York: Wi­ley-Liss.

Simp­son, G. 1945. The prin­ci­ples of clas­si­fi­ca­tion and a clas­si­fi­ca­tion of mam­mals. Bul­letin of the Amer­i­can Mu­seum of Nat­ural His­tory, 85: 1-350.

Step­pan, S., R. Ad­kins, J. An­der­son. 2004. Phy­logeny and di­ver­gence-date es­ti­mates of rapid ra­di­a­tions in Muroid ro­dents based on mul­ti­ple nu­clear genes.

Sys­tem­atic Bi­ol­ogy

Thomas, O. 1896. On the gen­era of ro­dents: an at­tempt to bring up to date the cur­rent arrange­ment of the order. Pro­ceed­ings of the Zo­o­log­i­cal So­ci­ety of Lon­don: 1012-1028.

Tull­berg, T. 1899. Uber das sys­tem der nageth­iere: eine phy­lo­genetis­che studie. Nova Acta Re­giae So­ci­etatis Sci­en­tiarum Up­salien­sis, 3: 1-514.