Cape Dune Mole Rat
Encyclopedia
The Cape dune mole rat is a species of solitary burrowing rodent
in the Bathyergidae family. It is endemic to South Africa
and named for the Cape of Good Hope
.
s, measuring 27 to 35 cm (10.6 to 13.8 ) in head-body length, with a short, 3 to 4 cm (1.2 to 1.6 ) tail. Males are generally much heavier than females, weighing anything from 570 to 1350 g (20.1 to 47.6 ), compared with typical female weights of 590 to 970 g (20.8 to 34.2 ).
Both sexes are sturdy, large-bodied rodents, with blunt snouts, cylindrical torsos and short limbs. The forefeet are heavily adapted for digging, with powerful curved claws. To enable to move more quickly through tight tunnels, the body has few visible external features; for example, there are no pinnae or scrotum
, and the penis retracts into a concealed sheath. Lip-like flaps of skin are able to close behind the incisors, preventing soil from falling into the mouth. The eyes are small, but not permanently closed.
Unlike its relative the naked mole rat
, the Cape dune species has a thick pelt of soft fur over its entire body. It is cinnamon-brown with greyish underparts, and few, if any markings. Like other blesmols, the Cape dune mole rat has a relatively low body temperature for its size, of about 35 °C (95 °F), and is not able to tolerate cold weather above ground.
, where it is found along the southern and western shores roughly between Vanrhynsdorp
and Port Elizabeth. Its natural habitat is sandy shorelines and river banks dominated by veldt grassland, sedges, and herbs.
. Their diet consists largely of grass and sedges pulled down into the burrow by the roots, although they also eat bulb
s and tuber
s from local plants such as Albuca
and cape tulips
. Since they almost never travel above ground, they are neither clearly nocturnal or diurnal, and may be active at any time of the day, although their peak activity seems to be during the afternoon.
Unusually for a blesmol, the Cape dune mole rat is not a social animal, with each individual having its own, isolated, burrow system. While most other blesmols dig through soil using their large, chiselling incisor
teeth, the loose, sandy soil of their native environment makes this approach less effective for Cape dune mole rats, which instead dig primarily with their claws, kicking the sand behind their bodies and eventually pushing it up to the surface as a molehill
. The burrows are entirely sealed, with no access to the surface, and stretch for between 50 and 420 m (164 and 1,378 ), over an area of around 0.27 hectare (0.667183940141245 acre). A single mole rat has been estimated to be able to excavate up to 500 kilograms (1,102.3 lb) of soil in a month, under ideal conditions.
Such burrows consist of numerous tunnels that the mole rat uses to search for food, and a few, deeper chambers used for nesting, food storage, and as latrines. Most tunnels are between 35 and 65 cm (13.8 and 25.6 ) below ground, but there are often a few blind-ending passages running as deep as 2 metres (6.6 ft), into which the animal retreats to escape from mole snake
s and other predators, blocking the tunnel behind itself as it does so. The burrows are protected from extremes of weather, and are constantly humid and hypoxic
.
Gestation
lasts for about two months, and results in the birth of a litter of up to six young, with three being typical. The young are initially blind and weigh 27 to 52 g (0.952396976838023 to 1.8 ). They open their eyes at seven days, begin to take solid food at twelve days, and are fully weaned
by the end of their first month. Litter mates frequently spar with one another, and disperse to establish their own burrow systems after around two months, by which time they have already reached nearly half the adult body weight. They live for over six years.
, along with the Namaqua dune mole rat. Both living species may have evolved from Bathyergus hendeyi, an extinct species rather smaller than the living forms, which inhabited the Cape Province
region of South Africa during the early Pliocene
, around four million years ago. Because of the large numbers of fossils found together, it has been suggested that this early species was social, like most other blesmols, but unlike its presumed living descendants; however, other possible explanations for this taphonomy
exist.
There are currently no recognised subspecies of Cape dune mole rat, although there have been few detailed studies of their genetic variability. It is possible that the species can hybridise with the Namaqua dune mole rat, with some suspected hybrids having been recovered from the Groenrivier region, where the two species live relatively close together.
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
in the Bathyergidae family. It is endemic to South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
and named for the Cape of Good Hope
Cape of Good Hope
The Cape of Good Hope is a rocky headland on the Atlantic coast of the Cape Peninsula, South Africa.There is a misconception that the Cape of Good Hope is the southern tip of Africa, because it was once believed to be the dividing point between the Atlantic and Indian Oceans. In fact, the...
.
Description
The Cape dune mole rat is the largest of all the blesmolBlesmol
The blesmols, also known as mole rats, or African mole-rats, are burrowing rodents of the family Bathyergidae. They represent a distinct evolution of a subterranean life among rodents much like the pocket gophers of North America, the tuco-tucos in South America, or the Spalacidae.- Distribution...
s, measuring 27 to 35 cm (10.6 to 13.8 ) in head-body length, with a short, 3 to 4 cm (1.2 to 1.6 ) tail. Males are generally much heavier than females, weighing anything from 570 to 1350 g (20.1 to 47.6 ), compared with typical female weights of 590 to 970 g (20.8 to 34.2 ).
Both sexes are sturdy, large-bodied rodents, with blunt snouts, cylindrical torsos and short limbs. The forefeet are heavily adapted for digging, with powerful curved claws. To enable to move more quickly through tight tunnels, the body has few visible external features; for example, there are no pinnae or scrotum
Scrotum
In some male mammals the scrotum is a dual-chambered protuberance of skin and muscle containing the testicles and divided by a septum. It is an extension of the perineum, and is located between the penis and anus. In humans and some other mammals, the base of the scrotum becomes covered with curly...
, and the penis retracts into a concealed sheath. Lip-like flaps of skin are able to close behind the incisors, preventing soil from falling into the mouth. The eyes are small, but not permanently closed.
Unlike its relative the naked mole rat
Naked Mole Rat
The naked mole rat , also known as the sand puppy or desert mole rat, is a burrowing rodent native to parts of East Africa and the only species currently classified in the genus Heterocephalus...
, the Cape dune species has a thick pelt of soft fur over its entire body. It is cinnamon-brown with greyish underparts, and few, if any markings. Like other blesmols, the Cape dune mole rat has a relatively low body temperature for its size, of about 35 °C (95 °F), and is not able to tolerate cold weather above ground.
Distribution and habitat
The Cape dune mole rat is found only in South AfricaSouth Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, where it is found along the southern and western shores roughly between Vanrhynsdorp
Vanrhynsdorp
Vanrhynsdorp, Western Cape is a settlement in West Coast District Municipality in the Western Cape province of South Africa.Vanrhynsdorp, situated in the centre of the Nama Karoo, provides a good base from which to explore the West Coast Mission Route as well as the Namaqualand and Karoo Mission...
and Port Elizabeth. Its natural habitat is sandy shorelines and river banks dominated by veldt grassland, sedges, and herbs.
Diet and behaviour
Like all mole rats, this species is strictly herbivorousHerbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
. Their diet consists largely of grass and sedges pulled down into the burrow by the roots, although they also eat bulb
Bulb
A bulb is a short stem with fleshy leaves or leaf bases. The leaves often function as food storage organs during dormancy.A bulb's leaf bases, known as scales, generally do not support leaves, but contain food reserves to enable the plant to survive adverse conditions. At the center of the bulb is...
s and tuber
Tuber
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction...
s from local plants such as Albuca
Albuca
Albuca is a genus of plants in the family Asparagaceae, subfamily Scilloideae. Most of the 100-140 species of bulbous plants in this genus are endemic to Southern Africa....
and cape tulips
Homeria
Homeria, commonly known as Cape tulips, is a genus of the botanical family Iridaceae, which has 32 species of corm-bearing perennial herbs. In addition, these plants are used as ornamental plants...
. Since they almost never travel above ground, they are neither clearly nocturnal or diurnal, and may be active at any time of the day, although their peak activity seems to be during the afternoon.
Unusually for a blesmol, the Cape dune mole rat is not a social animal, with each individual having its own, isolated, burrow system. While most other blesmols dig through soil using their large, chiselling incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
teeth, the loose, sandy soil of their native environment makes this approach less effective for Cape dune mole rats, which instead dig primarily with their claws, kicking the sand behind their bodies and eventually pushing it up to the surface as a molehill
Molehill
A molehill is a conical mound of loose soil raised by small burrowing mammals, including moles, but also similar animals such as mole-rats, marsupial moles and voles...
. The burrows are entirely sealed, with no access to the surface, and stretch for between 50 and 420 m (164 and 1,378 ), over an area of around 0.27 hectare (0.667183940141245 acre). A single mole rat has been estimated to be able to excavate up to 500 kilograms (1,102.3 lb) of soil in a month, under ideal conditions.
Such burrows consist of numerous tunnels that the mole rat uses to search for food, and a few, deeper chambers used for nesting, food storage, and as latrines. Most tunnels are between 35 and 65 cm (13.8 and 25.6 ) below ground, but there are often a few blind-ending passages running as deep as 2 metres (6.6 ft), into which the animal retreats to escape from mole snake
Mole snake
The mole snake is a species of snake in the family Pseudaspididae. It is native to much of southern Africa, and is the only member of the genus Pseudaspis. A study showed that P. cana are caught and consumed by the honey badger, among other species...
s and other predators, blocking the tunnel behind itself as it does so. The burrows are protected from extremes of weather, and are constantly humid and hypoxic
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...
.
Reproduction
The breeding season lasts from April to November, when rain is plentiful. Receptive individuals initially signal to each other by drumming on the floors of their burrows with their hind legs. After they have approached other, they lock their large incisor teeth together, until the female raises her tail and calls out prior to copulation.Gestation
Gestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
lasts for about two months, and results in the birth of a litter of up to six young, with three being typical. The young are initially blind and weigh 27 to 52 g (0.952396976838023 to 1.8 ). They open their eyes at seven days, begin to take solid food at twelve days, and are fully weaned
Weaning
Weaning is the process of gradually introducing a mammal infant, either human or animal, to what will be its adult diet and withdrawing the supply of its mother's milk.The process takes place only in mammals, as only mammals produce milk...
by the end of their first month. Litter mates frequently spar with one another, and disperse to establish their own burrow systems after around two months, by which time they have already reached nearly half the adult body weight. They live for over six years.
Taxonomy
The Cape dune mole rat is one of only two living species of the genus BathyergusBathyergus
Bathyergus is the genus of dune mole rats endemic to South Africa. It contains two species — B. janetta, the Namaqua Dune Mole Rat, and B. suillus, the Cape Dune Mole Rat.-References:...
, along with the Namaqua dune mole rat. Both living species may have evolved from Bathyergus hendeyi, an extinct species rather smaller than the living forms, which inhabited the Cape Province
Cape Province
The Province of the Cape of Good Hope was a province in the Union of South Africa and subsequently the Republic of South Africa...
region of South Africa during the early Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
, around four million years ago. Because of the large numbers of fossils found together, it has been suggested that this early species was social, like most other blesmols, but unlike its presumed living descendants; however, other possible explanations for this taphonomy
Taphonomy
Taphonomy is the study of decaying organisms over time and how they become fossilized . The term taphonomy was introduced to paleontology in 1940 by Russian scientist Ivan Efremov to describe the study of the transition of remains, parts, or products of organisms, from the biosphere, to the...
exist.
There are currently no recognised subspecies of Cape dune mole rat, although there have been few detailed studies of their genetic variability. It is possible that the species can hybridise with the Namaqua dune mole rat, with some suspected hybrids having been recovered from the Groenrivier region, where the two species live relatively close together.