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Spalax ehrenbergiMiddle East blind mole rat(Also: Palestine mole rat)

By Nicole Santarosa and Phill Moll

Geographic Range

Spalax ehrenbergi is widely distributed in the eastern Mediterranean region, from northeastern Libya through Egypt, Jordan, Syria, and southern Turkey. Within this region, these mole rats are found in fragmented areas with appropriate soils for burrowing. (Hutchins, 2004; Schlitter, et al., 2008)

Habitat

Though Middle East blind mole rats are not found in desert areas, they seem to prefer habitats with sandy and loamy soils. They are strictly fossorial and inhabit dry steppes, semi-desert, and agricultural areas, especially cultivated fields. They spend the vast majority of their lives in their underground burrows and tunnel systems. These are complex, with nesting chambers, storage areas, tunnels used for foraging, and aboveground mounds with sleeping chambers. Burrows are dug deeper in the hot months of the year. (Dewey, 2003; Hutchins, 2004; Schlitter, et al., 2008)

  • Range elevation
    0 to 2000 m
    0.00 to 6561.68 ft

Physical Description

Middle East blind mole rat body length ranges from 150 to 270 mm and the pelage is bluish, dark gray. They are characterized by their lack of an external tail, pinnae reduced to small ridges, and subcutaneous eyes. Other fossorial morphological adaptations include robustly built and streamlined bodies with large heads, powerful limbs, and small claws. Males are larger than females. (Dewey, 2003; Hutchins, 2004; Schlitter, et al., 2008)

The dental formula for Spalax ehrenbergi is 1/1, 0/0, 0/0, 3/3 = 16. The two large incisors are orthodont and are oriented in front of the lips so that the incisors can be used to dig even when the mouth is closed. The cheek teeth are rooted and display enamel patterns that resemble the letters "z" and "s." (Hutchins, 2004; Musser and Carleton, 2005)

Spalax ehrenbergi has a highly polymorphic karyotype with over 30 chromosomal forms. It has been posited that some of these forms are likely to be distinct species. It has been suggested that at least four distinct cryptic species (Spalax carmeli, Spalax galili, Spalax golani, and Spalax judae) exist. (Musser and Carleton, 2005; Nevo and Shkolnik, 1974)

  • Sexual Dimorphism
  • male larger
  • Range mass
    250 to 400 g
    8.81 to 14.10 oz
  • Range length
    150 to 270 mm
    5.91 to 10.63 in
  • Range basal metabolic rate
    0.62 to 1.03 cm3.O2/g/hr

Reproduction

Females only mate with one male for each breeding season, but may mate with different males throughout their lifetime, making them serially monogamous. Spalax ehrenbergi mating behavior is categorized into three stages: agonistic, courtship, and copulation. Courtship takes place during the winter season, which is the only time males and females will be found in overlapping territory. This species is highly aggressive, with severe aggressive displays occurring within and between the sexes. Due to their aggressive nature, courtship is a very long process involving the male and female engaging in repeated mating displays until their aggressive behavior is attenuated. Seismic signaling is used to initiate the first contact between the male and female's respective burrows. This involves both males and females drumming their heads against the ceilings of their burrows to create vibrations. The mating pair begins with face-to-face touching of their incisors which proceeds to nibbling and courtship calls, which contributes to reducing the intensity of the aggressive displays between the pair. After the courtship ritual the male will dig a “copulation hollow” which is where the actual mating will take place. After the pair becomes habituated to the hollow the female will initiate copulation by turning her back towards the male. Immediately after copulation the male will fill in the “copulation hollow” and the pair will separate and return to solitary lifestyles. (Dewey, 2003; Gazit and Terkel, 2000; Heth, et al., 1987; Nevo, 1969; Zuri and Terkel, 1998)

Middle East blind mole rats breed in the winter, from November to March. Females construct elaborate breeding mounds and nesting chambers in preparation for breeding. Gestation lasts 34 days and the average litter size is 3 to 4 (range 1 to 5) pups. Young are born from January to April. As the offspring develop, aggressive interactions between the pups increase to the point where they are forced to disperse from each other. Once the pups begin dispersing, the mother reciprocates aggressive displays to aid in kin dispersal and ensure her young do not attempt to settle in her territory. Young are independent at 4 to 6 weeks old. Time to first reproduction is not reported, but is likely to be within their first year of life. (Dewey, 2003; Gazit and Terkel, 2000; Heth, et al., 1987; Nevo, 1969; Zuri and Terkel, 1998)

  • Breeding interval
    Females seem to breed once yearly.
  • Breeding season
    Middle East blind mole rats breed in the winter, from November to March.
  • Range number of offspring
    1 (low)
  • Average number of offspring
    3 to 4
  • Average gestation period
    34 days
  • Range time to independence
    4 to 6 weeks

Females provide sole parental care. In a study done by Gazit and Terkel (2000), males exhibited limited parental care and intermittently brought food to the female’s territory if the males had acquired a large food surplus during the wet season. The young are born naked and helpless but develop quickly, leaving the nest and becoming independent at 4 to 6 weeks old. (Dewey, 2003; Gazit and Terkel, 2000; Zuri and Terkel, 1998)

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

Lifespan/Longevity

Middle East blind mole rats lives around 3 years in the wild, but can live up to 15 years in captivity. Maximum lifespan in the wild is given as 4.5 years. (Dewey, 2003; Heth, et al., 1988)

  • Range lifespan
    Status: wild
    4.5 (high) years
  • Average lifespan
    Status: wild
    3 years
  • Range lifespan
    Status: captivity
    15 (high) years

Behavior

Middle East blind mole rats are fossorial and highly aggressive. Generally single individuals occupy burrow systems and they are quite territorial. Middle East blind mole rats are active during the day. Middle East blind mole rats dig complex underground burrows and establish complex networks of tunnels in pursuit of food. (Heth, et al., 1988; Nevo, et al., 1975; Zuri and Terkel, 1998)

Home Range

Home range size (burrow extent) is not reported in the literature.

Communication and Perception

Middle East blind mole rats are completely blind, their eyes being beneath a layer of skin. They rely heavily on vocalizations, olfaction, and touch. Six distinct vocalizations are used: attack, crying, invitation, courting, release, and threat calls. Courtship calls consist of a low murmur that reduces aggression between potential mates. All Spalax ehrenbergi calls are at a low frequency and are specialized for low frequency hearing. Head thumping against tunnel ceilings is also used in vibrational communication, which has shown to be advantageous in long distance communication and is used to signal territoriality and initiate mating rituals. Although the eyes of Spalax ehrenbergi are not used for visual purposes, they are still photoreceptive. In a study done by Sanyal et al. (1990), it was shown that the eyes are used for detecting photoperiodicity, which allows them to distinguish the various stages of the day. (Gazit and Terkel, 2000; Heth, et al., 1987; Heth, et al., 1988; Nevo, 1969; Nevo, et al., 1975; Sanyal, et al., 1990)

Food Habits

Middle East blind mole rats are strict herbivores and primarily feed on the underground roots, stems, tubers, and seeds of plants. They dig extensive underground tunnels in search of food and use underground chambers to store excess, harvested food. (Dewey, 2003; Hutchins, 2004; Schlitter, et al., 2008)

  • Plant Foods
  • leaves
  • roots and tubers
  • wood, bark, or stems
  • seeds, grains, and nuts

Predation

Spalax ehrenbergi has adapted to a strict fossorial lifestyle, which provides good protection from most predators. No natural predators are reported in the literature, although they are sometimes persecuted by humans. (Hutchins, 2004; Schlitter, et al., 2008)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Spalax ehrenbergi is a primary consumer and through its diet of underground plant roots, tubers, and seeds; it shapes and defines that plant biodiversity and availability in an ecosystem. The extensive burrowing and tunneling activitie of this species also affects the water, nutrient, and air composition of soils. (Hutchins, 2004; Schlitter, et al., 2008)

Economic Importance for Humans: Positive

Although Middle East blind mole rats are often regarded as agricultural pests, they are useful in research. They have been instrumental in locating significant and important archeological sites by bringing buried artifacts and bones to the surface. They have also acted as an important species in the medical research field. Their hypoxic fossorial environment has resulted in some unique adaptations that are of interest to medical communities concerned with treating ischemia and cancer. Lastly, populations seem to be undergoing rapid speciation and there is great chromosomal and allozyme diversity within the species. It is currently being utilized as an important model species to study and elucidate the patterns and mechanisms behind speciation. (Avivi, et al., 1999; Hutchins, 2004; Nevo, 1969; Nevo, et al., 1975; Schlitter, et al., 2008)

Economic Importance for Humans: Negative

Middle East blind mole rats eat roots and tubers and are considered an agricultural pest in some areas because they eat crop and disturb them with their digging. Libyans believe that touching Spalax ehrenbergi results in blindness, although to this date they have not been shown to be a vector for any human diseases. (Hutchins, 2004; Schlitter, et al., 2008)

  • Negative Impacts
  • crop pest

Conservation Status

According to the IUCN Red List, Spalax ehrenbergi is considered “data deficient,” which means there is not enough known about their population numbers to make an accurate assessment. Populations are thought to be decreasing, perhaps as a result of intensified agriculture in some areas. Middle East blind mole rats are considered common in appropriate habitat and are considered agricultural pests in some areas, where they may be persecuted. (Dewey, 2003; Schlitter, et al., 2008)

Contributors

Nicole Santarosa (author), University of Michigan-Ann Arbor, Phill Moll (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor, Tanya Dewey (editor), Animal Diversity Web.

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

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.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
drug

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease

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.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

vibrations

movements of a hard surface that are produced by animals as signals to others

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Avivi, A., M. Resnick, E. Nevo, A. Joel, A. Levy. 1999. Adaptive hypoxic tolerance in the subterranean mole rat Spalax ehrenbergi: the role of vascular endothelial growth factor. Federation of European Biochemical Societies., 452: 133-140.

Dewey, T. 2003. Rats, Mice, and Relatives V: All other rats, mice, and relatives. Pp. 281-298 in M Hutchins, A Evans, J Jackson, D Kleiman, J Murphy, D Thoney, eds. Grzimek's Animal Life Encyclopedia, Vol. 16, 2nd ed Edition. Detroit: Gale.

Gazit, I., J. Terkel. 2000. Reproductive behavior of the blind mole-rat (Spalax ehrenbergi) in a seminatural burrow system. Canadian Journal of Zoology, Volume 78, Issue 4: 570-578. Accessed March 28, 2009 at http://proquest.umi.com/pqdlink?Ver=1&Exp=03-27-2014&FMT=7&DID=54325918&RQT=309&clientId=17822&cfc=1.

Heth, G., E. Frankenberg, E. Nevo. 1988. "Courtship" Call of Subterranean Mole Rats (Spalax ehrenbergi): Physical Analysis. Journal of Mammology, Volume 69, Issue 1: 121-125. Accessed March 28, 2009 at http://www.jstor.org/sici?sici=0022-2372(1988)69:1%3C121:%27COSMR%3E2.0.CO;2-&cookieSet=1#&origin=sfx%3Asfx.

Heth, G., E. Frankenberg, A. Raz, E. Nevo. 1987. Vibrational communication in subterranean mole rats (Spalax ehrenbergi). Behavioral Ecology and Sociobiology, Volume 21, Number 1: 31-33. Accessed March 28, 2009 at http://www.springerlink.com/content/g66568ht846377wk/.

Hutchins, M. 2004. Rats, mice, and relatives V. Pp. 281-295 in D Kleiman, V Geist, M Mcdade, eds. Grizimek's Animal Life Encyclopedia, Vol. 16, 2nd Edition. New York: Thomson and Gale.

Musser, G., M. Carleton. 2005. Mammal Species of the World. Washington, D.C.: Smithsonian Institution Press.

Nevo, E., A. Shkolnik. 1974. Adaptive metabolic variation of chromosome forms in mole rats, Spalax. Cellular and Molecular Life Sciences, 30/7: 724-726.

Nevo, E. 1969. Mole Rat Spalax ehrenbergi: Mating Behavior and Its Evolutionary Significance. Science, Volume 163, Issue 3866: 484-486. Accessed March 28, 2009 at http://www.jstor.org/sici?sici=0036-8075(1969)163:3866%3C484:MRSEMB%3E2.0.CO;2-#&origin=sfx%3Asfx.

Nevo, E., G. Naftali, R. Guttman. 1975. Aggression Patterns and Speciation. Proceedings of the National Academy of Sciences of the United States of America, Volume 72, Issue 8: 3250-3254. Accessed March 28, 2009 at http://www.jstor.org/stable/info/64545?seq=1.

Sanyal, S., H. Jansen, W. de Grip, E. Nevo, W. Jong. 1990. The Eye of the Blind Mole Rat, Spalax ehrenbergi Rudiment With Hidden Funtion?. Investigative Ophthalmology & Visual Science, Vol. 31, No. 7: 1398-1404. Accessed April 09, 2009 at http://www.iovs.org/cgi/reprint/31/7/1398.

Schlitter, D., G. Shenbrot, B. Kryštufek, M. Sozen. 2008. "Spalax ehrenbergi. In: IUCN 2008. 2008 IUCN Red List of Threatened Species" (On-line). Accessed March 30, 2009 at http://www.iucnredlist.org/details/14326.

Zuri, I., J. Terkel. 1998. Ontogeny of agonistic behaviour in dispersing blind mole rats (Spalax ehrenbergi). Aggressive behavior, Volume 24, Issue 6: 455-470. Accessed March 28, 2009 at http://cat.inist.fr/?aModele=afficheN&cpsidt=2424378.

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