The blind mole-rats, also known as the fossorial or subterranean mole rats, are a

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

(Spalacinae) of

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

s in the family

Spalacidae 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, m ...

, found in

eastern Europe Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural and socio-economic connotations. Its eastern boundary is marked by the Ural Mountain ...

and

western Western may refer to: Places *Western, Nebraska, a village in the US *Western, New York, a town in the US *Western Creek, Tasmania, a locality in Australia *Western Junction, Tasmania, a locality in Australia *Western world, countries that id ...

and

central Asia Central Asia is a region of Asia consisting of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. The countries as a group are also colloquially referred to as the "-stans" as all have names ending with the Persian language, Pers ...

. The

hystricognath The Hystricognathi are an infraorder of rodents, distinguished from other rodents by the bone structure of their skulls. The masseter medialis (a jaw muscle) passes partially through a hole below each eye socket (called the infraorbital foram ...

mole-rats of the family Bathyergidae are completely unrelated, but some other forms are also in the family

Zokor Zokors are Asia, Asiatic burrowing rodents resembling Spalacidae, mole-rats. They include two genera: ''Myospalax'' and ''Eospalax''. Zokors are native to much of China, Kazakhstan, and Siberia, Siberian Russia. Traditionally, zokors were though ...

s (subfamily Myospalacinae), root rats, and bamboo rats (subfamily Rhizomyinae) are spalacids also sometimes referred to as mole rats. Blind mole-rats are in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

, but are unique enough to be given a separate

, Spalacinae. Alternate opinions on

taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

consider the blind mole-rats to be the only members of the family

and rank other spalacid subfamilies as full families. Other authors group all members of the superfamily

Muroidea The Muroidea are a large Taxonomic rank, superfamily of rodents, including mice, rats, voles, hamsters, lemmings, Gerbillinae, gerbils, and many other relatives. Although the Muroidea originated in Eurasia, they occupy a vast variety of habitat ...

into a single family,

Muridae The Muridae, or murids, are either the largest or second-largest family of rodents and of mammals, containing approximately 870 species, including many species of mice, rats, and gerbils found naturally throughout Eurasia, Africa, and Australia. ...

. The Spalacinae contains two

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

and eight

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

. Some authorities treat all species as belonging to a single genus, ''

Spalax ''Spalax'' is a genus of rodent in the family Spalacidae, subfamily Spalacinae (blind mole-rats). It is one of two extant genera in the subfamily Spalacinae, alongside '' Nannospalax''.' Species in this genus are found in eastern Europe an ...

'', but more recent studies indicate a deep divergence between both lineages dating back to the

Late Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million ye ...

, supporting them as being distinct genera.'''' Blind mole-rat diggings 02

Spalacinae mole-rats are truly blind. Their very small eyes are completely covered by a layer of skin. Unlike many other

fossorial A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamand ...

s, blind mole-rats do not have enlarged front claws and do not appear to use their forearms as a primary digging tool. Digging is almost exclusively conducted using their powerful front teeth, which are separated from the rest of the mouth by a flap of skin. When a blind mole-rat closes its mouth, its incisors are still on the outside. Blind mole-rats may have evolved from spalacids that used their front limbs to dig, because their

olecranon process The olecranon (, ), is a large, thick, curved bony process on the proximal, posterior end of the ulna. It forms the protruding part of the elbow and is opposite to the cubital fossa or elbow pit (trochlear notch). The olecranon serves as a lever ...

es are large relative to the rest of their arms. The olecranon process is a part of the

ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...

bone where muscles attach, and digging animals tend to have enlarged olecranon processes to provide a large surface for their large and powerful

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

s to attach. Because they are completely blind, blind mole-rats have been important laboratory animals in tests on how

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

s and eye

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

s function. Although blind mole-rats have only atrophied subcutaneous eyes and are sightless, their

circadian rhythm A circadian rhythm (), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours. Circadian rhythms can refer to any process that originates within an organism (i.e., Endogeny (biology), endogenous) and responds to the env ...

is kept. A few publications, such as Avivi ''et al.'', 2002, have proven that the circadian genes that control the biological clock are expressed in a similar manner as in sighted, above-ground mammals.

Classification

* Subfamily Spalacinae - blind mole-rats ** Genus ''

'' *** Mehely's blind mole-rat'', S. antiquus'' *** Sandy blind mole-rat, ''S. arenarius'' *** Giant blind mole-rat, ''S. giganteus'' *** Bukovina blind mole-rat, ''S. graecus'' *** Oltenia blind mole-rat, ''S. istricus'' (possibly

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

) *** Greater blind mole-rat, ''S. microphthalmus'' *** Kazakhstan blind mole-rat, ''S. uralensis'' *** Podolsk blind mole-rat, ''S. zemni'' ** Genus '' Nannospalax'' - small-bodied mole-rats *** Subgenus ''Nannospalax'' **** Middle East blind mole-rat or Palestine mole-rat, ''N. ehrenbergi'' *** Subgenus ''Mesospalax'' **** Lesser blind mole-rat, ''N. leucodon'' **** Anatolian blind mole-rat or Nehring's blind mole-rat, ''N. xanthodon''

References

{{Taxonbar, from=Q14153702 Spalacidae