Animal Diversity Web

Diversity

The family Spalacidae is a diverse old world group of fossorial and semi-fossorial rodents. This family consists of 36 species in 6 genera distributed among four subfamilies: the Myospalacinae, the Rhizomyinae, the Spalacinae, and the Tachyoryctinae. (Norris, et al., 2004)

Geographic Range

Spalacids are old world rodents. They range from the Ukraine through the Balkans and the eastern Mediterranean, into Africa as far west as Libya and as far south as northern Tanzania, and in Asia from western China south to Sumatra and north to southern Siberia. (Corbert, 1984; Nowak, 1999; Vaughan, et al., 2000)

• Biogeographic Regions
• palearctic
  • native
• oriental
  • native
• ethiopian
  • native

Habitat

Spalacids construct burrows in grasslands, scrublands, agricultural areas, and forests. They avoid deserts, preferring moist or semi-moist soils. Many inhabit mountainous regions, reaching elevations of up to 4,000 meters. (Corbert, 1984; Nowak, 1999)

• Habitat Regions
• temperate
• tropical
• terrestrial

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

• Other Habitat Features
• agricultural
• riparian

Physical Description

Spalacids are adapted for a fossorial or semifossorial lifestyle. They have stout, rounded, molelike bodies, reduced eyes and external ears, short, dense fur, and short limbs. Their heads are broad and they have powerful neck muscles. The wide incisors project forward in front of the lips in all except for the myospalacines (which dig with their forearms instead of with their incisors) (Norris et al. 2004). Body sizes for this family range from the diminutive Spalax leucodon, measuring 130 mm in body length and weighing just 100 grams, to the hefty Rhizomys sumatrensis, measuring 480 mm and weighing up to to 4 kg. In some species, such as Tachyoryctes splendens, males are larger, and in others, there is no discernible sexual dimorphism. (Corbert, 1984; Flynn, 1990; Norris, et al., 2004; Nowak, 1999; Vaughan, et al., 2000)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike
• male larger

Reproduction

The only mating systems that have been reported for spalacids are polygyny and polygynandry. Males and females of most spalacid species only associate for a short time during courtship and mating. (Nowak, 1999; Nowak, 1999; Nowak, 1999)

• Mating System
• polygynous
• polygynandrous (promiscuous)

Spalacids usually have either one or two litters per year. Females of some species have a postpartum estrus, becoming pregnant again as soon as they give birth. Other females only have a single litter in their lifetime. The time of breeding varies between and within species, and depends on location. Gestation lasts between four and seven weeks, and anywhere from one to five young are born per litter. (Corbert, 1984; Nowak, 1999)

• Key Reproductive Features
• semelparous
• iteroparous
• seasonal breeding
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • internal
• viviparous
• post-partum estrous

Female spalacids constuct underground nests in which they give birth to altricial young. Males do not help care for their offspring. Females of most species nurse their young for four to six weeks, and the young leave the nest at two to three months. (Corbert, 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
  • protecting
    • female

Lifespan/Longevity

Maximum longevity for species in this family is 4.5 years, but most probably do not live more than a year in the wild. (Nowak, 1999)

Behavior

Spalacids spend most of their lives underground, although some may come to the surface occasionally to forage. They are active year round, with timing of daily activity varying by species. These rodents construct elaborate tunnel systems, digging with their incisors (spalacines, rhizomyines and tachyoryctines) or foreclaws (rhizomyines, tachyoryctines and myospalacines) and using their hind feet or snout to push soil out behind them. Tunnel systems include well-defined areas for sleeping, foraging, and defecating. Spalacids are solitary, with each animal inhabiting its own burrow system and defending a territory that varies in size depending on the age, sex, and size of the individual. Generally, spalacids are sedentary, but a few species migrate seasonally when food becomes scarce. (Corbert, 1984; Flynn, 1990; Nevo, 1999; Norris, et al., 2004; Nowak, 1999; Savic and Nevo, 1990; Vaughan, et al., 2000)

• Key Behaviors
• terricolous
• fossorial
• diurnal
• nocturnal
• crepuscular
• motile
• migratory
• sedentary
• solitary
• territorial

Communication and Perception

Because they spend most of their time underground, spalacids do not have much use for vision, and therefore, their eyes are much reduced, although they remain functional and light sensitive in some. Their sense of touch is well-developed, and many have tactile hairs on the sides of their head. They also have good hearing and sense of smell. Pheromones and scent-marking are important means of communication in this group. Some species are known to communicate with each other by drumming their heads against the walls of their tunnels and sensing the vibrations created by others. Many are known to make grunting or hissing noises when threatened. (Nevo, 1999; Nowak, 1999)

• Communication Channels
• acoustic
• chemical

• Other Communication Modes
• pheromones
• scent marks
• vibrations

• Perception Channels
• visual
• tactile
• acoustic
• vibrations
• chemical

Food Habits

The spalacid diet consists largely of roots, bulbs, rhizomes, and other underground plant parts. Shoots, leaves, seeds, fruit, insects, and other arthropods are eaten occasionally by some species. Many store large quantities of food in their underground burrow systems. (Corbert, 1984; Nowak, 1999; Vaughan, et al., 2000)

• Primary Diet
• carnivore
  • insectivore
  • eats non-insect arthropods
• herbivore
  • folivore
  • frugivore
  • granivore
• omnivore

• Foraging Behavior
• stores or caches food

Predation

Spalacids sometimes fall prey to nocturnal hunters, such as owls, when they emerge above ground to forage. Other predators include snakes, eagles, and small mammalian carnivores. When confronted by a predator, spalacids may fight fearlessly, rushing the enemy and biting viciously with their formidable incisors. Their fossorial lifestyle may be their primary defense against predators. (Flynn, 1990; Nowak, 1999)

• Known Predators

  • owls (Strigidae)
  • snakes (Serpentes)
  • eagles (Accipitridae)
  • mammalian carnivores (Carnivora)

Ecosystem Roles

Spalacids are primary consumers, and they are a food source for a number of predators. Because of their extensive digging activity, spalacids affect the distribution of nutrients, air, and water in the soil, and therefore impact plant diversity. Also, other small animals sometimes shelter in their burrows. Finally, spalacids are parasitized by nematodes, ixodid ticks, gamasid mites, and fleas. (Flynn, 1990; Ganzorig, et al., 1999; Litvinov and Sapegina, 2003; Zhang, et al., 2004; Zhang, et al., 2003)

• Ecosystem Impact
• creates habitat
• soil aeration

Economic Importance for Humans: Positive

Many species of spalacids are eaten by native tribes, and the skin and bones of some are used as charms and for medicinal purposes, respectively. Also, some species of spalacids are important for medical research. (Chariyalertsak, et al., 1997; Nowak, 1999; Zhang, et al., 2003; Zhou, et al., 2004)

• Positive Impacts
• food
• body parts are source of valuable material
• source of medicine or drug
• research and education

Economic Importance for Humans: Negative

When present in agricultural areas, spalacids may feed on the roots of crops and cause considerable damage. (Nowak, 1999)

• Negative Impacts
• crop pest

Conservation Status

Of the 36 species in this family, 7 are listed as vulnerable (Chinese zokors, Eospalax fontanierii, sandy blind mole rats, Spalax arenarius, giant blind mole rats, Spalax giganteus, Balkan blind mole rats, Spalax graecus, greater blind mole rats, Spalax microphthalmus, lesser blind mole rats, Spalax leucodon, and big-headed mole rats, Tachyoryctes macrocephalus), 3 are listed as lower risk (three Myospalax species), and 2 are listed as data-deficient (two Tachyoryctes species) by the IUCN. (IUCN, 2004)

• IUCN Red List [Link]

  Not Evaluated

Other Comments

The earliest known fossil spalacid is about 20 million years old, from the lower Miocene in Greece. For the most part, the fossil distribution of this family overlaps with the current geographic distribution. (Nevo, 1999; Savic and Nevo, 1990)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

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

References

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