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.
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.
Biogeographic Regions: palearctic (Native ); oriental (Native ); ethiopian (Native )
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.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike; male larger
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.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; chaparral ; forest ; scrub forest ; mountains
Other Habitat Features: agricultural ; riparian
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.
Foraging Behavior: stores or caches food
Primary Diet: carnivore (Insectivore , Eats non-insect arthropods); herbivore (Folivore , Frugivore , Granivore ); omnivore
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.
Ecosystem Impact: creates habitat; soil aeration
- nematodes Nematoda
- ixodid ticks Ixodidae
- gamasid mites Gamasida
- fleas Siphonaptera
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.
- owls (Strigidae)
- snakes (Serpentes)
- eagles (Accipitridae)
- mammalian carnivores (Carnivora)
Life History and Behavior
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.
Communication Channels: acoustic ; chemical
Other Communication Modes: pheromones ; scent marks ; vibrations
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
Maximum longevity for species in this family is 4.5 years, but most probably do not live more than a year in the wild.
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.
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.
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.
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)
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:113
Specimens with Barcodes:54
Species With Barcodes:14
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.
Relevance to Humans and Ecosystems
When present in agricultural areas, spalacids may feed on the roots of crops and cause considerable damage.
Negative Impacts: crop pest
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.
Positive Impacts: food ; body parts are source of valuable material; source of medicine or drug ; research and education
The Spalacidae, or spalacids, are a family of rodents in the large and complex superfamily Muroidea. They are native to eastern Asia, the Horn of Africa, the Middle East, and southeastern Europe. It includes the blind mole-rats, bamboo rats, root rats, and zokors. This family represents the oldest split (excluding perhaps the Platacanthomyinae) in the muroid superfamily, and comprises animals adapted to a subterranean way of life. These rodents were thought to have evolved adaptations to living underground independently until recent genetic studies demonstrated they form a monophyletic group. Members of the Spalacidae are often placed in the family Muridae along with all other members of the Muroidea.
Spalacids are mouse- to rat-sized rodents, adapted to burrowing and living underground. They have short limbs, wedge-shaped skulls, strong neck muscles, large incisor teeth, and small eyes and external ears. In the zokors, which dig primarily with their feet, rather than their teeth, the front claws are also massively enlarged. These features are least extreme in the bamboo rats, which spend at least some of their time above ground, foraging for food. They are most highly developed in the blind mole-rats, whose eyes are completely covered by skin, and entirely lack external ears or tails.
All of the spalacid species dig extensive underground burrows, which may include storage chambers for food, latrine chambers, and breeding nests. They are generally solitary animals, and do not share their tunnel complexes with other individuals. All the species are herbivores, feeding on roots, bulbs, and tubers.
They give birth to litters of up to six young after a gestation period of between three and seven weeks, depending on the species. As with many other muroids, the young are born blind, hairless, and helpless. They may stay with the mother for several months before setting off to establish their own burrows, although some species disperse as soon as they are weaned.
Norris et al. listed several characteristics present in all members of this family which distinguish them from the rest of the muroids, (the clade Eumuroida). These are "the reduction or absence of external eyes, reduced pinnae, stocky body, short tail (<50% head and body length), broad rostrum, triangular-shaped braincase, infraorbital canal ovoid shape and does not extend ventrally to the roof of the palate, zygomatic plate absent or much reduced, nasolacrimal canal inside infraorbital canal, incisive foramina small to medium-sized, extensive neck musculature and prominent points of attachment on the occipitum, minimal reduction in M3 relative to M1 and M2, and a distinct orientation of the manubrium of the malleus bone."
- Subfamily Myospalacinae - zokors
- Subfamily Rhizomyinae
- Tribe Rhizomyini - bamboo rats
- Tribe Tachyoryctini
- Genus Tachyoryctes - mole-rats
- Ankole mole-rat, T. ankoliae
- Mianzini mole-rat, T. annectens
- Audacious mole-rat, T. audax
- Demon mole-rat, T. daemon
- Kenyan African mole-rat, T. ibeanus
- Big-headed mole-rat, T. macrocephalus
- Naivasha mole-rat, Tachyoryctes naivashae
- King mole-rat, T. rex
- Ruanda mole-rat, T. ruandae
- Rudd's mole-rat, T. ruddi
- Embi mole-rat, T. spalacinus
- East African mole-rat, T. splendens
- Storey's African mole rat, T. storeyi
- Genus Tachyoryctes - mole-rats
- Subfamily Spalacinae
- Genus Spalax - blind mole-rats
- Sandy mole-rat, S. arenarius
- Mount Carmel blind mole-rat, S. carmeli
- Middle East blind mole-rat, S. ehrenbergi or Nannospalax ehrenbergi
- Upper Galilee Mountains blind mole-rat, S. galili
- Giant mole-rat, S. giganteus
- Golan Heights blind mole-rat, S. golani
- Balkan mole-rat, S. graecus
- Judean Mountains blind mole-rat, S. judaei
- Lesser mole-rat, S. leucodon
- Greater mole-rat, S. microphthalmus
- Munzur mole-rat, S. munzuri
- Nehring's blind mole-rat, S. nehringi
- Kazakhstan blind mole-rat, S. uralensis
- Podolsk mole-rat, S. zemni
- Genus Spalax - blind mole-rats
- Corbet, Gordon (1984). Macdonald, D., ed. The Encyclopedia of Mammals. New York: Facts on File. pp. 666–671. ISBN 0-87196-871-1.
- Norris, R.W. et al. (2004). "The phylogenetic position of the zokors (Myospalacinae) and comments on the families of muroids (Rodentia)". Molecular Phylogenetics and Evolution 31 (3): 972–978. doi:10.1016/j.ympev.2003.10.020. PMID 15120394.
- Jansa, S. A. and 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, and F. Catzeflis. 2001. Evolutionary history of the most speciose mammals: molecular phylogeny of muroid rodents. Molecular Biology and Evolution, 17:280-293.
- Steppan, S. J., R. A. Adkins, and J. Anderson. 2004. Phylogeny and divergence date estimates of rapid radiations in muroid rodents based on multiple nuclear genes. Systematic Biology, 53:533-553.
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