Spalacidaeblind mole rats, African mole rats, zokors, and bamboo rats

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)

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)

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)

  • 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)

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)

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)

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)

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)

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)

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)

Commensal/Parasitic Species

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)

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.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

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.

carnivore

an animal that mainly eats meat

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

crepuscular

active at dawn and dusk

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.

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

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

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

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).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

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

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

pheromones

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

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

polygynous

having more than one female as a mate at one time

riparian

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

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

semelparous

offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.

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

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

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.

year-round breeding

breeding takes place throughout the year

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