There are a total of nine species of mole-rat in the genus Crypotmys, all of which are distributed across the semi-arid regions of Africa. Fossilized remains can be traced back to the Oligocene. Only one other species of mole-rat, from the genus Heterocephalus, is defined as being eusocial.
Like other members of the genus Cryptomys, Damaraland mole-rats often act aggressively. They use squeaks, grunts, and growls when confronting each other in order to create and maintain a dominance hierarchy.
Associated with these vocalizations, there are often aggressive physical encounters. Larger individuals often use tail-pulling as a means of forcing smaller individuals to perform more labor. Physcial contact may also be involved in reproductive supression of members of the colony.
It is believed that these animals lack the ability to see, although the surfaces of their eyes are used to detect air currents. Vibrissae located along the body are used for detecting their surroundings. This being the case, visual signals are highly unlikely to play any role in communication.
Chemical pheromones in the urine of the dominant female may be used to suppress sexual activity in subordinates.
Communication Channels: tactile ; acoustic ; chemical
Other Communication Modes: pheromones ; vibrations
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
Cryptomys damarensis is a common species and therefore has no special status.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
As with other members of the family Bathyergidae, mole-rats are often seen as pests in that they can consume large amounts of valuable agricultural products and private vegetable gardens. They have been known to chew through underground cables and cause damage to agricultural machinery.
Negative Impacts: crop pest
As with other fossorial mammals, Damaraland mole-rats contribute to soil tilling and water infiltration. They are also hunted for human consumption. For research and education, they present an interesting adaptation to life in arid environments.
Positive Impacts: food ; research and education
Damaraland mole-rats are capable of tilling large quantities of soil which helps in its aeration. Their tunnels also aid in water infiltration, helping to supply water to deep-rooted trees.
Ecosystem Impact: soil aeration
Damaraland mole-rats are primarily herbivorous, eating mainly roots, bulbs, tubers, and aloe leaves. They also consume invertebrates, such as earthworms, cockchafer larvae, and white ants.
Animal Foods: insects; terrestrial worms
Plant Foods: leaves; roots and tubers
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Folivore )
Damaraland mole-rats, Crytomys damarensis, live in southwestern and central Africa, primarily in Botswana and West Zambia.
Biogeographic Regions: ethiopian (Native )
Damaraland mole-rats are subterranean and inhabit semi-arid regions. This includes woodland, savannah, and secondary forest habitats.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; scrub forest
Other Habitat Features: agricultural
Lifespan and longevity is currently unknown for Damaraland mole-rats, although individuals of the closely related species, Cryptomys hottentotus, have lived nearly 10 years in captivity. Cryptomys damarensis probably has a similar lifespan.
Status: captivity: 11.9 years.
Head and body length is 90 to 270 mm, and tail length is 10 to 30 mm. The breeding male and female within a colony are the largest individuals. The male is slightly larger than the female.
The body is slender with legs that are short, making this species well adapted for fossorial life. Also, the ears lack external pinnae. The pelage is thick, with sensitive guard hairs, sometimes referred to as vibrissae. Large, protuberant incisors are used extensively for borrowing. The lips close behind these digging tools to prevent dirt from entering the mouth.
Range mass: 86 to 202 g.
Range length: 100 to 300 mm.
Sexual Dimorphism: male larger
Other Physical Features: endothermic ; bilateral symmetry
Average basal metabolic rate: 0.418 W.
Specific predators of Damarland mole-rats have not yet been identified. Other species of subterranian mole-rats are thought to suffer from predation by snakes. Snakes are the most likely predator of these animals as well.
Damaraland mole-rats have evolved a cooperative breeding system where within a colony, a high reproductive skew is maintained by only a single female and male breeding. The precise mechanism by which this operates is uncertain, although it is likely that both behavioral (i.e. aggression) and chemical suppression (i.e. pheromones) are used.
Mating System: monogamous ; eusocial
In wild populations, these animals are thought to breed once annually. Captive colonies of Damaraland mole-rats are capable of breeding year-round. In captivity, two litters per year are common. After a gestation of 78 to 112 days, a litter of one to three highly precocial young is born. Young nurse until about 82 days of age.
Females can reach reproductive maturity at 73 weeks of age. However, since reproduction is supressed in all but the breeding pair, it is difficult to estimate how early reproductive maturity might be reached. Age at dispersal and mechanism of dispersal of the young are not known.
Breeding interval: In the wild, Damaraland mole-rats breed once each year.
Breeding season: Breeding season varies geographically.
Range number of offspring: 1 to 3.
Range gestation period: 78 to 112 days.
Average weaning age: 82 days.
Average age at sexual or reproductive maturity (female): 73 weeks.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
Average birth mass: 9 g.
Average number of offspring: 2.5.
Average age at sexual or reproductive maturity (female)
Sex: female: 511 days.
A pregant female spends most of her time within a chamber designated as the nesting area. The mother provides young with milk for about 82 days. Certain members of the colony help care for the juveniles through grooming, huddling together for warmth, feeding, and by preventing them from straying.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Protecting: Male, Female); inherits maternal/paternal territory