Tiny insectivorous burrowing rodents native to Southern Africa are the Golden moles.
They form the Chrysochloridae family and are taxonomically distinct from the true moles, the Talpidae family, and other mole-like families, all of which imitate evolutionary convergence to varying degrees.
Scientific Classification
- Kingdom: Animalia
- Phylum: Chordata
- Class: Mammalia
- Order: Afrosoricida
- Suborder: Golden mole
- Family: Golden mole
Characteristics and Affinities
The golden mole has short legs, powerful digging claws, dense fur that repels dirt and moisture, and toughened skin, especially on the head, like most burrowing mammals with similar habits.
Their eyes are non-functional, and their skin is coated with fur. Small holes are just external faces.
Golden moles, in particular, bear a remarkable resemblance to Australia’s marsupial moles, the Notoryctidae family, which they mimic so suggestively that the marsupial/placental divide did not stand simultaneously; some argued that they were related.
The opinion that the Golden mole is a very primitive placental and has many mole-like specializations close to specializations in marsupial moles may have affected the debate.
The rhinarium is a largely dry, leathery pad that covers the nostrils when the animal is digging. They, too, resemble marsupial moles in this regard.
Some authors say that their primary sense of touch is touch, and they are susceptible to vibrations that may signify an approaching hazard.
However, the findings on the middle ear malleus are noted below. The scale of the species varies from about 8 centimeters (3.1 to about 20 centimeters (7.9 in).
They have muscular shoulders, and the forelimbs are dramatically modified for digging; except for a broad, pick-like third claw on the third toe, all of the toes on the forefeet have been reduced.
The fifth digit is missing, and the vestigial digits are the first and fourth. The adaptations of the hind feet are less drastic, maintaining all five toes and weaving as an adaptation to the powerful backward shoveling of the soil loosened by the front claws.
The Golden mole was known at one time as primitive. Supporting reasons for this included that they were supposed to have originated in Gondwana, that they had a low metabolic rate of rest, and that when inactive, they could turn off thermoregulation.
They have a cloaca, like the Tenrecs, and males lack a scrotum. Nevertheless, these points are no longer highly suggestive as undeveloped “reptilian mammals” for Golden moles; others are seen as adaptations to regional climatic conditions.
When resting or during cold weather, going into a torpor helps them conserve power and reduce urgent food requirements.
Similarly, especially powerful kidneys have been established, and most animals do not need water. If they fall into the water, they appear to drown easily.
Ecology and Habits
Most Golden mole species live almost entirely underground in their chosen habitats, underneath grass veld, woodland, swamps, deserts, or mountainous terrain.
However, Chrysospalax species tend to forage above ground in leaf litter in woods or meadows. Eremitalpa species, such as Grant’s Golden mole, live in the sandy Namib desert, where they can not form tunnels because the sand collapses.
Instead, they “swim” through the loose sand throughout the day when they have to seek cover, using their large claws to paddle and dive down some 50 cm to where it is bearably cold.
They enter a state of torpor and thus save energy there. Instead of wasting energy moving sand, they emerge to forage on the surface at night. Their main prey is termites that live under isolated clumps of grass and may fly in search of food for 6 kilometers a night.
By listening to wind-rustled grass-root stresses and the head-banging warning signals of termites, they search for enticing clumps, none of which can be easily detected above ground, so they stop occasionally and dip their heads to listen under the sand.
Most other animals build foraging shallow burrows and deeper permanent burrows for residence.
Relatively complex in shape, residential burrows can penetrate as far as a meter below ground and include deep chambers for use as bolt-holes and restrooms for other chambers.
Like molehills, they force excavated soil up to the surface or compact it into the tunnel walls. Tiny insects, earthworms, or tiny vertebrates such as lizards or burrowing snakes feed on them.
To identify most of their prey, they depend on their sense of hearing, and the cochleas of a variety of Golden mole species have been found to belong and be highly coiled, which may suggest a greater ecological reliance on auditory indications of low frequency than we see in Talpid moles.
Some species also have hypertrophied ossicles of the middle ear, especially the malleus, which is adapted to detecting seismic vibrations.
There is some obvious convergent evolution in the Amphisbaenidae family regarding burrowing reptiles.
Reproductivity
Inside the burrow system, females give birth to one to three hairless young people in a grass-lined nest. Breeding happens all year round.
The adults are solitary and can actively defend their burrowing territories from intruders, particularly where resources are relatively scarce.
Conservation Status
Of the 21 Golden mole species, no less than 11 are threatened with extinction. Sand mining, poor agricultural practices, increasing urbanization, and predation by domestic cats and dogs are the primary causes.
History
Golden mole is one of 18 species of blind and tailless burrowing insectivores living in sub-Saharan Africa (order Chrysochloridae). They are sufficiently distinct to constitute their mammalian order from other moles and insectivores.
A cylindrical body, small arms, and no external tail are in the Golden moles; under the skin are tail vertebrae.
Their triangular head ends at the muzzle in a leathery pad; their degenerate eyes are coated with skin and fur, and external ears are missing. The skin is durable and is bound to the body loosely.
The four front digits bear powerful claws, two of which, like a pickax, are long and shaped. Membranous skin connects the five hind digits.
The fur is long and slightly coarse in two species, but short, smooth, and thick in all others. It varies from dark grey to brownish tones and chestnut to black, with the radiance of violet, orange, purple, or bronze.
Most species are nocturnal, although some are also active in the daytime. Loamy or sandy soils are preferred; clay and compact soils are avoided.
Golden moles are coming to the surface following heavy rainfall. Insects, earthworms, and lizards are eaten by Golden moles.
In shallow subsurface caves, some fly and forage; others excavate burrows as deep as 50 cm (20 inches), with entrances marked by soil mounds.
With the leathery muzzle, forefeet, and claws, the soil is loosened and then forced with the claws and muzzle under the body.
The hind feet drive the debris out of the burrow and down it. Southern Africa’s Golden mole (Eremitalpa granti) of Grant is a sand-dune inhabitant.
It does not stay in burrows but flies on or just below the dune surface at night, using its front limbs and muzzle to “swim” through the sand. It buries itself in soft sand, down to 35 cm throughout the day.
Forests, savannas, grasslands, rocky hillsides, sandy riverbeds, and dunes range from coastal lowlands to 3,300 meters (10,800 feet)—Golden moles. Several species reportedly live in cultivated fields and on the fairways of golf courses.
The largest is South Africa’s giant Golden mole (Chrysospalax trevelyani) with a 20 to 24 cm (7.9 to 9.4 inches) long body; it is a forest dweller that dens in burrows but moves along the surface and forages.
Grant’s Golden mole is the smallest, weighing less than an ounce, with a body 8 to 9 cm long. One or two young babies are born with Golden moles.
Paleontology and Classification
Within the family Golden mole, the only family of the order Chrysochloridae which belongs to a larger group of mammals referred to as insectivores, Golden moles are classified into seven genera. African Tenrecidae (family Tenrecidae) may be their closest relatives.
Based on fossils, the family’s evolutionary past can be traced back to Africa’s Early Miocene Epoch (23.8 to 11.2 million years ago).
- Order Chrysochloridae
- One family from sub-Saharan Africa. 2 fossil genera.
- Family Golden mole (Golden moles)
- Eighteen species in six genera.
- Genus Chlorotalpa (African Golden moles)
- Golden mole species.
- Genus Amblysomus (South African Golden moles)
- Four species.
- Genus Chrysochloris (Cape Golden moles)
- Three species.
- Genus Chrysospalax (large Golden moles)
- Two species.
- Genus Cryptochloris (secretive Golden moles)
- Two species.
- Genus Calcochloris (yellow-Golden mole)
- One species.
- Genus Eremitalpa (Grant’s Golden mole)
- One species.
