Family Spalacidae
blind mole rats, African mole rats, zokors, and bamboo rats

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)

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, Ryan, and Czaplewski, 2000)

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)

Jansa and Weksler (2004) include a summary of the long, complicated taxonomic history of the family Spalacidae (as well as that of the rest of Muroidea). Alston (1876) designated Spalacidae as a family including the subfamilies Spalacinae and Bathyerginae, and classified the genus Myospalax seperately under the subfamily Siphneinae and the family Muridae. Thomas (1896) included two subfamilies under Spalacidae, Rhizomyinae and Spalacinae, and classified Myospalacinae as a subfamily of Muridae. Miller and Gidley (1918) placed the subfamilies Myospalacinae and Spalacinae in the family Spalacidae, separate from the Rhizomyidae, and Ellerman (1940, 1941) and Simpson (1945) proposed similar classifications, except that the former placed the Tachyoryctinae and the Myospalacinae within Muridae and the latter placed Myospalacini within Cricetidae. Chaline et al. (1977) did away with the family Spalacidae altogether, instead placing the subfamilies Spalacinae and Myospalacinae in the Cricetidae and the Tachyoryctoidinae and Rhizomyinae in the Rhizomyidae. Additionally, some authors have classified all the subfamilies of the current Spalacidae within the Muridae (Vaughan et al. 2000; Musser and Carleton 1993; Nowak 1991). However, recent molecular evidence has shown that the genera Rhizomys, Tachyoryctes, Myospalax, and Spalax form a monophyletic group sister to all other Muroidea, and hence these have been placed within a separate family, the Spalacidae (Jansa and Weksler 2004; Norris et al. 2004; Steppan et al. 2004). This classification actually follows that proposed by Tullberg (1899) over 100 years ago.

In recent years it has been suggested that the Myospalacinae are most closely related to the Cricetinae, based on a phylogenetic analysis using one Myospalax specimen (Michaux et al. 2001). However, other studies using multiple specimens have not supported this view, and instead place Myospalacinae basal to the other subfamilies within the Spalacidae (Jansa and Weksler 2004; Norris et al. 2004; Steppan et al. 2004). (Alston, 1876; Chaline, Mein, and Petter, 1977; Ellerman, 1940; Ellerman, 1941; Jansa and Weksler, 2004; Michaux, Reyes, and Catzeflis, 2001; Miller and Gidley, 1918; Musser and Carleton, 1993; Norris et al., 2004; Nowak, 1999; Simpson, 1945; Steppan, Adkins, and Anderson, 2004; Thomas, 1896; Tullberg, 1899; Vaughan, Ryan, and Czaplewski, 2000)

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, Ryan, and Czaplewski, 2000)

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)

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, Ryan, and Czaplewski, 2000)

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)

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, Ryan, and Czaplewski, 2000)

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)

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, Liu, and Du, 2004; Zhang, Zhang, and Liu, 2003)

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

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, Zhang, and Liu, 2003; Zhou, Zhou, and Zhang, 2004)

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)